The issue presented in instant case involves the proper distribution of refunds received by the appellee utilities as a result of prior period overpayments to their natural gas supplier.
The Commission looked to G.S. 62436(c) to determine whether the supplier refunds should be retained by the utilities or distributed to their customers. Prior to 1981, G.S. 62436(c) provided as follows:
(c) If any refund is made to a distributing company operating as a public utility in North Carolina of charges paid to the company from which the distributing company obtains the energy, service or commodity distributed, the Commission may, if practicable, in cases where the charges have been included in rates paid by the customers of the distributing company, and where the company had a reasonable return exclusive of the refund, require said distributing company to distribute said refund among said customers in proportion to their payment of the charges refunded.
*477The Public Staff argues that G.S. 62-136(c) does not apply to the refunds. They contend that G.S. 62433(f) is the applicable statute. This provision, which became effective 21 July 1971, reads as follows:
(f) Unless otherwise ordered by the Commission subsections (b), (c) and (d) shall not apply to rate changes of utilities engaged in the distribution of natural gas bought at wholesale by the utility for distribution to consumers to the extent such rate changes are occasioned by changes in the wholesale rate of such natural gas. The Commission may permit such rate changes to become effective simultaneously with the effective date of the change in the wholesale cost of such natural gas, or at such other time as the Commission may direct. This subsection shall not prohibit the Commission from investigating and changing unreasonable rates in accordance with the provisions of this Chapter. The public utility shall give such notice, which may include notice by publication, of the changes to interested parties as the Commission in its discretion may direct.
The Public Staff urges us to find G.S. 62433(f) controlling on the theory that these supplier refunds are, in effect, retroactive rate reductions in the utilities’ wholesale cost of gas for the period 1958-1971. As such, the refunds are matters “occasioned by changes in the wholesale rate of such natural gas” as contemplated by G.S. 62433(f). They also contend that G.S. 62433(f) is the more specific statutory provision because it applies solely to changes in the wholesale rates of natural gas, whereas G.S. 62436(c) applies to refunds received by any type of North Carolina distributing company utility.
To the contrary, we are of the opinion that G.S. 62436(c) more specifically applies to supplier refunds received by natural gas distributing utilities. G.S. 62433(f) is a mechanism whereby a natural gas utility may pass on to its customers supplier increases or decreases without going through the costly and protracted procedures of a general rate case. Utilities Commission v. CF Industries, Inc., 39 N.C. App. 477, 479, 250 S.E. 2d 716, 717-18 (1979). G.S. 62433(f) deals only with rate changes. G.S. 62436(c), however, specifically sets forth the criteria pursuant to which refunds should be distributed.
*478We hold that G.S. 62436(c) is the proper statute to be applied in determining the appropriate distribution of these supplier refunds.
The appellee utilities contend, however, that G.S. 62436(c) does not govern those refunds attributable to overpayments made prior to 1 January 1964, the effective date of the statute. An examination of the Commission’s orders in instant case reveals that the Commission also determined that G.S. 62436(c) did not apply to all of the refunds received in 1978. The orders specifically provided that the refunds attributable to the years 1958 through 1963 were being distributed pursuant to the Commission’s implied powers under Chapter 62. Only those refunds attributable to overpayments made after 1 January 1964 were distributed pursuant to the dictates of G.S. 62436(c).
We conclude that this bifurcated analysis is unnecessary. G.S. 62436(c) speaks in terms of when the refund is received by the utilities, not to the period of time to which the refunds relate. The statute says that “if any refund is made” to a public utility, the Commission may order the refund to be distributed among the utility’s customers if the statutory requirements are met. Since these refunds were received by Piedmont and Public Service well after the effective date of the statute, we hold that G.S. 62436(c) governs the distribution of all of the refunds at issue here.1
We next address the question of whether the statutory requirements of G.S. 62436(c) have been met in this case.
Prior to the 1981 amendment, G.S. 62436(c) permitted the distribution of refunds to a utility’s customers only if the following three conditions were met:
(1) It was practicable to distribute the refunds,
(2) The charges had been included in rates paid by the customers, and
*479(3) The company had a reasonable return exclusive of the refund.
The statute provided that the refund would be distributed among the customers of the utility “in proportion to their payment of the charges refunded.”
The Court of Appeals interpreted this language to mean that the refunds must be made to those customers who actually paid the overcharges. In reversing the Utilities Commission, Judge Arnold wrote:
Determination of the identity of those customers to whom refunds might be due here, and of the relative proportion of their interests, in our view, would be impracticable since the charges in question relate to periods ranging from ten-twenty-three years prior to the supplier refunds. Therefore, one of the statutory prerequisites is unfulfilled, no refund is called for, and the Commission’s contrary conclusion was erroneous.
56 N.C. App. at 450, 289 S.E. 2d at 83.
We agree with the Court of Appeals that prior to the 1981 amendment, G.S. 62436(c) required that refunds be distributed only to those individuals who actually paid the overcharges. We see no reason to assume that the legislature intended for the utilities to refund money to individuals who could not possibly have paid any of the charges refunded, as would unquestionably be the case if these refunds were distributed to current customers as the Commission directed. The requirement that refunds be made to customers in proportion to their payment of the charges refunded compels us to conclude that the legislature contemplated that refunds be made only to those customers who paid rates including the producer overcharges.
Our interpretation also follows from the requirement that “the charges have been included in rates paid by the customers.” Obviously, the overcharges were included, if at all, in the rates paid by customers who were receiving service from Piedmont and Public Service during the period to which these refunds relate. This evidences to us an intention of retrospective reimbursement which is not accomplished by the Commission’s order in this case.
*480The Public Staff urges us to interpret the language “in proportion to their payment of the charges refunded” as referring to the proportion of company revenues received from each class of customers. Their position is that the Commission properly applied this language in ordering the utilities to distribute the refunds among current customers on the basis of, and in proportion to, the prior payment of the overcharges during 1958 through 1971 as determined by customer class.
We do not agree with this interpretation. As stated earlier, we are of the opinion that the legislature intended for the refunds to be made in proportion to each customer’s usage in the refund period during which he paid excess charges. We are reluctant to superimpose a requirement that the refunds be made on the basis of customer class for if this had been the legislature’s intention, it would have been a simple proposition for them to have explicitly provided for such a method of distribution. We find no language in the statute requiring distribution by customer class.
Our conclusion is strengthened by the legislature’s 1981 amendment to G.S. 62436(c). It is no longer required that the refund be practicable and that the utility have a reasonable return exclusive of the refund in order for the Commission to direct a customer refund. More importantly, however, the statute no longer provides for distribution of the refunds to customers in proportion to their payment of the charges refunded. The Commission is now authorized to require the distribution of refunds “among the distributing company’s customers in a manner prescribed by the Commission.” Clearly, the Commission is now empowered to order the distribution of supplier refunds to either current or past customers, utilizing whatever method the Commission deems most appropriate.
In construing a statute with reference to an amendment, the presumption is that the legislature intended to change the law. Childers v. Parker’s, Inc., 274 N.C. 256, 260, 162 S.E. 2d 481, 483-84 (1968). This is especially so, in our view, when the statutory language is so drastically altered by the amendment. We also consider it significant that the 1981 Session Laws, c. 460, s. 2, provide that the amendment shall not be applied retroactively. This is strong evidence that the legislature understood that the amendment occasioned a change in, rather than a clarification of, existing law.
*481Finally, we agree with the Court of Appeals that it would not be practicable to make refunds to those customers served by the utilities during the period to which these refunds relate. The undisputed evidence discloses that the gas companies do not have records revealing the names of customers served during that period or the amounts of gas purchased by those customers. Consequently, the practicability requirement of the statute has not been met in instant case and no refund is called for.
We hold that the Commission erred in ordering a total refund to the utilities’ customers because the statute required their distribution to the actual customers who paid rates including the overcharges and such a distribution would be impracticable.
We find it unnecessary to discuss the remaining assignments of error since our holding requires that the judgment of the Court of Appeals be affirmed.
Affirmed.
Justice CARLTON concurs in the result.. Implicit in this reasoning is the conclusion that all refunds received after 28 May 1981 will be governed by the 1981 amendment to G.S. 62-136(c). 1981 Sess. Laws c. 460, s. 1. As such, the Commission will be empowered to order distribution of supplier refunds to current or past customers, by customer class or on an individual basis. The amendment clearly provides that the method and manner of distribution will be left to the Commission’s sound discretion.