DISSENTING OPINION BY
Judge LEAVITT.The majority affirms a class action judgment against a tax collector based upon Act 61 violations and unjust enrichment. Act 6, a usury statute, has zero application to a municipality’s collection of delinquent taxes, and unjust enrichment is not available where there is a written contract governing the parties’ conduct. To otherwise hold, the majority has accepted plaintiffs’ strained legal theories. I cannot and, respectfully, dissent.
Portnoff Law Associates and Michelle Portnoff (together Portnoff) appeal two orders of the Court of Common Pleas of Philadelphia County (trial court) directing Portnoff to pay a total of $2,347,006.46 in damages and attorneys’ fees to a certified class of delinquent taxpayers.2 Portnoff is in the business of collecting taxes for municipalities and school districts located throughout the Commonwealth. Delinquent Taxpayers sued Portnoff for collecting fees in excess of the delinquent taxes owed. Specifically, Delinquent Taxpayers asserted that Portnoff improperly passed *1283the municipality’s attorney fees and administrative fees for PortnofPs collection of delinquent taxes along to Delinquent Taxpayers.
Initially, Delinquent Taxpayers prevailed and were awarded damages and attorneys’ fees in the amount of $5,213,670.08. However, the act commonly referred to as the Municipal Claims and Tax Lien Act3 (MCTLA) was then amended, with a retroactive effective date, to authorize municipalities to recover their attorney fees and costs of collection from their delinquent taxpayers.4 The retroactive effective date of January 1, 1996, eviscerated Delinquent Taxpayers’ first judgment, which covered Portnoff s collections in years 2000-2002.5
On remand, the trial court removed the attorney fees from the original judgment. This left a $35 fee that Portnoff charged municipalities to open a file and give notice, by certified mail, to taxpayers. The municipalities contracted to pay Portnoff this fee. For example, Portnoff s contract with the Allentown City School District to recover delinquent real estate taxes states:
School District agrees to enact any and all resolutions required by state law to impose the legal fees set forth herein upon the delinquent property owner. School District hereby retains Portnoff to provide all delinquent property owners with the notice as required by Act 1 of 1996 at a cost of $35.00 per notice. This administrative expense shall be paid to Portnoff Law Associates by the School District. The School District may charge this expense to the taxpayer and be reimbursed upon payment by the delinquent taxpayer.
Reproduced Record at 364a (R.R. -) (emphasis added). As set forth in the contract, the $35 fee covered the notices required by the MCTLA, verifying the property owner and address, postage for certified mailings, review of delivery receipts and, in some cases, setting up a payment plan with the delinquent taxpayers.
The trial court held that the $35 fee was actionable and awarded damages. This award began with the $510,855 in administrative fees that Portnoff collected from Delinquent Taxpayers and added $18,493.55 in interest. The court then doubled that total, i.e. $529,348.55, in accordance with Section 502 of Act 6. This resulted in total damages of $1,058,697.10. The trial court then granted Delinquent Taxpayers’ motion for all attorney fees incurred.6 The trial court awarded Delinquent Taxpayers $1,267,386.25 in attorney fees and $20,923.11 in costs. The total of the two judgments was $2,347,006.46.
Portnoff challenges the award in its entirety. Portnoff observes that the *1284MCTLA specifically allows municipalities to recover fees they incur in the collection of unpaid taxes, including the $35 fee charged by Portnoff. As such, Portnoff properly collected the $35 fee from Delinquent Taxpayers on behalf of the municipalities. In any case, Portnoff argues that Act 6 simply does not apply to tax collection matters. Because the $35 fee was a matter of contract between Portnoff and the municipalities, Portnoff argues that Delinquent Taxpayers cannot bring an unjust enrichment claim. In no case, Port-noff asserts, can Delinquent Taxpayers pursue the agent of the municipalities, Portnoff, without including the municipalities as necessary and indispensable parties. I agree.
Act 6, the Loan Interest Protection Law, enacted a wide-ranging regulatory regime for the stated purpose of establishing “a flexible maximum lawful interest rate for residential mortgages ... [tied to] the Monthly Index of Long Term United States Government Bond Yields.... ” Section 301 of Act 6, 41 P.S. § 301.7 Act 6 focuses on mortgage loans, but it also limits the interest a lender can charge a borrower on any loan. Act 6 regulates settlement and finance charges, lest these charges be used as a vehicle to exceed the maximum rate of interest allowed in Act 6. For example, Act 6 limits the charges that can be imposed on a borrower to those specified in the definition of “actual settlement costs.”8 Act 6 does not make any reference to the administrative “charges” a municipality can pay a tax collector and then recover from a delinquent taxpayer. Act 6 is simply irrelevant to Delinquent Taxpayers’ quest for justice.
To argue otherwise, Delinquent Taxpayers rely upon Section 502 of Act 6, which states:
A person who has paid a rate of interest for the loan or use of money at a rate in excess of that provided for by this act or otherwise by law or has paid charges prohibited or in excess of those allowed by this act or otherwise by law may recover triple the amount of such excess interest or charges in a suit at law against the person who has collected such excess interest or charges; Provided, that no action to recover such excess shall be sustained in any court of this Commonwealth unless the same shall have been commenced within four years from and after the time of such payment. Recovery of triple the amount of such excess interest or charges, but not the actual amount of such excess interest or charges, shall be limited to a four-year period of the contract.
41 P.S. § 502 (emphasis added). There are numerous problems with Delinquent Taxpayers’ reliance upon Section 502.
First, Section 502 does not create a cause of action for a violation of Act 6, let alone another statute, such as the MCTLA. All Section 502 does is authorize triple damages, assuming a cause of action under Act 6. The cause of action is created by Section 504 of Act 6, and it states:
Any person affected by a violation of the act shall have the substantive right to *1285bring an action on behalf of himself individually for damages by reason of such conduct or violation, together with costs including reasonable attorney’s fees and such other relief to which such person may be entitled under law.
41 P.S. § 504 (emphasis added). Here, there was no violation of Act 6. This is because nothing in Act 6 makes it unlawful to over-charge a taxpayer for costs associated with the collection of his delinquent taxes. Absent a violation of Act 6, there is nothing to redress in a Section 504 action and no damages to triple in accordance with Section 502.
Second, the operative language in Section 502 is “for the loan or use of money.” This means that treble damages are available where a person has paid: (1) a rate of interest in excess of that allowed in Act 6 in connection with the loan or use of money; or (2) paid any charges that were either prohibited or in excess of those allowed in Act 6 in connection with the loan or use of money. Delinquent Taxpayers simply disregard this opening clause “for the loan or use of money.”
Third, Delinquent Taxpayers’ action for overpayment of tax collection charges cannot be reconciled with Section 503 of Act 6, which authorizes a debtor, who brings an action for a violation of Act 6, to recover attorney fees. Section 503 states:
(a) If a borrower or debtor, including but not limited to a residential mortgage debtor, prevails in an action arising under this act, he shall recover the aggregate amount of costs and expenses determined by the court to have been reasonably incurred on his behalf in connection with the prosecution of such action, together with a reasonable amount for attorney’s fee.
(b) The award of attorney’s fees shall be in an amount sufficient to compensate attorneys representing debtors in actions arising under this act....
(c)Any time attorneys’ fees are awarded pursuant to any provision of this act, a borrower or debtor shall not be entitled to duplicate recovery of attorneys’ fees....
41 P.S. § 503 (emphasis added). Act 6 creates rights for borrowers and debtors. A delinquent taxpayer is not a “borrower” or a “debtor,” as assumed by the trial court.
The terms “debt” and “debtors” are terms of art. Long ago our Supreme Court explained that:
Every debt of course is an obligation, but every obligation is not a debt.... A debt is a sum or money due by contract, express or implied. But a tax is not a debt. It is not founded upon contract. It does not establish the relation of debt- or and creditor between the taxpayer and the [governmental entity].
In re Moorehead’s Estate, 289 Pa. 542, 553, 137 A. 802, 806 (1927) (emphasis added) (citations omitted). A debt arises from a contract; indeed, Section 502 of Act 6 refers, specifically, to the “period of the [loan] contract.” 41 P.S. § 502. A tax, as explained by our Supreme Court, does not arise from a contract, and a delinquent taxpayer is not a “debtor” within the meaning of Act 6.
In short, Section 502 did not create a cause of action by which Delinquent Taxpayers could pursue their tax collector. Delinquent Taxpayers take one phrase in Section 502 and run far afield with it. Their expansive read of the phrase “charges ... in excess of those allowed by this act or otherwise by law” in Section 502 to create a cause of action against a tax collector, as opposed to a lender, cannot be harmonized with the rest of Section 502, let alone the rest of Act 6. Section 502 does *1286not give every Pennsylvania citizen who has paid a charge in excess of any charge established in any statute or ordinance in Pennsylvania a cause of action under Act 6, which does not even purport to regulate the costs of pursuing delinquent taxes. Rather, the purpose of Act 6 is to establish “a flexible maximum lawful interest rate for residential mortgages.” Section 301 of Act 6, 41 P.S. § 301. It is not a violation of Act 6 for a municipality to pay a tax collector a $35 fee to set up a file, and it is not a violation for the municipality to recover that fee from the taxpayer.
In any case, even if one accepts the creative notion that Section 502 establishes a cause of action to recover fees paid in excess of those allowed in any Pennsylvania statute, ordinance or regulation, it does not apply to the $35 fee in question. This is because the MCTLA expressly authorized that fee. The MCTLA defines “charges” to mean “all sums paid or incurred ... to file, preserve and collect unpaid taxes.” Section 1 of the MCTLA, 53 P.S. § 7101. The MCTLA then states that a municipality may recover any “charges, expenses, and fees” it incurs in the collection of delinquent taxes as payment to its tax collectors. Id. The MCTLA does not specify the amount of “charges, expenses, and fees” that can be recovered by a municipality, but it provides that such “charges, expenses, and fees” must be reasonable. Id. Delinquent Taxpayers presented no evidence whatsoever to prove that the $35 charge was unreasonable.
Nor does Delinquent Taxpayers’ unjust enrichment theory work. Unjust enrichment, or quasi-contract, cannot be invoked where parties have a written contractual agreement. Third National Bank & Trust Co. of Scranton v. Lehigh Valley Coal Co., 353 Pa. 185, 193, 44 A.2d 571, 574 (1945). The contract between Portnoff and the municipalities was the basis for the $35 fee, and the contract must be the basis of any damage action. The contract also specified that the municipality’s $35 fee could be recovered from the taxpayer. A contract that violates statute or public policy may be void or voidable. But Delinquent Taxpayers do not challenge the enforceability of the contract. Instead, they assert that Portnoff retained the $35 fee and did not remit it to the municipality. If so, the municipality may have a breach of contract claim against Portnoff, but the taxpayers do not.9
To advance a claim for unjust enrichment, benefits must have been conferred under circumstances where the receipt and retention of those benefits is inequitable. See Konidaris v. Portnoff Law Associates, Ltd., 884 A.2d 348, 355 (Pa.Cmwlth.2005), reversed on other grounds, 598 Pa. 55, 953 A.2d 1231 (2008). An unjust enrichment defendant must receive and retain a benefit. Id. The burden of proving the receipt and retention of benefits lies with the plaintiff, here the Delinquent Taxpayers. Commonwealth ex rel. Pappert v. TAP Pharmaceutical Products, Inc., 885 A.2d 1127, 1137 (Pa.Cmwlth.2005).
Delinquent Taxpayers did not prove Portnoff retained any benefit. Michelle Portnoff testified that the municipalities paid the $35, as required by their contract. Portnoff built that fee into the amount collected from the Delinquent Taxpayers. Ms. Portnoff also testified that whenever the $35 fee was collected, it was remitted to the municipality. The trial court did not credit her testimony. However, not *1287crediting testimony does not constitute substantial evidence to prove the opposite, i.e., that Portnoff retained the $85 fee. See Yi v. State Board of Veterinary Medicine, 960 A.2d 864, 875 (Pa.Cmwlth.2008). Because Delinquent Taxpayers did not prove that Portnoff retained the $85 fee recovered from Delinquent Taxpayers, it did not prove Portnoff received any benefit, which is the sine qua non of unjust enrichment.10
Even if Portnoff did retain the $35 fee, instead of remitting it to the municipalities, this does not mean that the fee should be paid to Delinquent Taxpayers. By contract, those fees are owed to the municipalities. There is nothing “just” about awarding Delinquent Taxpayers monies that, as a matter of contract, are owed to the municipalities by Portnoff. The law does not correct one wrong by creating a second wrong.
All of this underscores the reason why the municipalities had to be parties to the litigation. Failure to join an indispensable party deprives the Court of subject matter jurisdiction and is fatal to a cause of action. Polydyne, Inc. v. City of Philadelphia, 795 A.2d 495, 496 (Pa.Cmwlth.2002). A party is considered “indispensable” if their rights are “so connected with the claims of the litigants that no decree can be made without impairing those rights.” Id. (quoting Vernon Township Water Authority v. Vernon Township, 734 A.2d 935, 938 n. 6 (Pa.Cmwlth.1999)). Most particularly, it violates due process to adjudicate claims that compromise the rights of the absent party. Montella v. Berkheimer Associates, 690 A.2d 802, 803 (Pa.Cmwlth.1997). If Portnoff holds monies owed to the municipalities, then the judgment here deprives the municipalities of their ability to recover those fees from Portnoff. The municipalities are indispensable parties.
Tax collectors have been reviled since their profession was established. See, e.g., Matthew 9:9-13 (New International Version) (explaining the Pharisees’ view that tax collectors were “sinners” to be shunned at dinner parties). However, the law must be followed even when it is hard to do so. To allow Delinquent Taxpayers to use Act 6 in the manner authorized by the majority is error and will produce unintended consequences. Judge Roy Wilkinson, Jr., one of the original judges of this Court and a justice of the Pennsylvania Supreme Court, once cautioned, “If we throw away the law to beat the Devil, what shall we use as a shield when he turns on us?” Hilton v. State Employees Retirement Board, 23 Pa.Cmwlth. 639, 353 A.2d 883 (1976) (Wilkinson, Judge, dissenting) (quoting a statement attributed to Sir Thomas More).
Indeed.
I would reverse.
. Act of January 30, 1974, P.L. 13, as amended, 41 P.S. §§ 101-605.
. Plaintiffs, Beverly Roethlein, Robert Alba-nese, Jerry Konidaris, and Theodara Konidar-is (together Delinquent Taxpayers) represent a class of taxpayers whose property taxes were delinquent and whose municipalities had con-traded with Portnoff for their collection. The class was certified to cover all property owners in the Commonwealth who received communications regarding delinquent taxes from Portnoff, and ultimately amounted to over 16,000 taxpayers.
. Act of May 16, 1923, P.L. 729, as amended, 53 P.S. §§ 7101-7505.
. In Konidaris v. Portnoff Law Associates, Ltd., 598 Pa. 55, 953 A.2d 1231 (2008), the retroactive amendment was held constitutional.
. The exact class year ran from November 27, 2000, to November 26, 2002.
. Delinquent Taxpayers requested $1,838,461 in attorney fees, using a lodestar approach. The trial court reduced it to $1,267,386.25. Portnoff argues that the trial court’s award of attorney fees was excessive because most of Delinquent Taxpayers' attorney fees were incurred in advancing claims Delinquent Taxpayers failed to prevail on such as, inter alia, their argument that Portnoff illegally shifted its attorneys fees onto Delinquent Taxpayers, which was adjudicated in our Supreme Court's decision in Konidaris v. Portnoff Law Associates, Ltd., 598 Pa. 55, 953 A.2d 1231 (2008). Thus, Portnoff argues the trial court’s award of attorney fees does not accurately reflect what was actually incurred by Delinquent Taxpayers to recover the $35 administrative fee collected by Portnoff.
. Portnoff notes this intent by pointing to the legislative history of this Act and noting that Senator Zemprelli stated "[t]his bill was intended as a mortgage interest bill.” Port-noff's Brief at 21 (citing Pa. Senate Journal, January 15, 1974, p. 1334).
. Generally, Section 101 allows "reasonable” charges for things such as insurance and a title search to be charged to a borrower as "actual settlement costs.” 41 P.S. § 101. However, it specifically limits the amount of a "service charge” to be no more than "one percent of the original bona fide principal amount of the loan, except ... in the case of a construction loan, [which] shall not exceed two percent[.]” Id.
. The fact that Delinquent Taxpayers were not a party to the contract does not open the door to unjust enrichment. See D.A. Hill Co. v. CleveTrust Realty Investors, 524 Pa. 425, 434, 573 A.2d 1005, 1010 (1990).
. In Konidaris, the Supreme Court upheld the General Assembly’s retroactive amendment to the Municipal Claims and Tax Liens Act. The $35 fee covered the notice requirements in the MCTLA. The retroactive amendment allowed municipalities to recover their attorney fees and other costs incurred to collect unpaid taxes. The majority relies upon a cryptic quote from Pentlong Corp. v. GLS Capital, Inc., 780 A.2d 734 (Pa.Cmwlth.2001), affirmed in part, reversed in part, 573 Pa. 34, 820 A.2d 1240 (2003), to hold the $35 not an allowable charge under the MCTLA. Pent-long stated that allowable charges are "taxed as costs.” The majority does not explain why the $35 fee is not an allowable fee "taxed as a cost.”