Charles Wade sued Dr. Thomas Whalen for medical malpractice arising out of the doctor’s participation in surgery on Wade’s mother. She died on August 12, 1992, allegedly as a result of the malpractice. Wade filed suit on August 10, 1994, two days before the running of the statute of limitation.1 Wade did not serve process on Dr. Whalen until eight months later on April 10, 1995. Dr. Whalen moved for summary judgment, asserting expiration of the time limitation. The court denied the motion and its renewal, but ultimately it did grant summary judgment. The issue is whether the trial court abused its discretion in finding Wade did not show diligent service of process.
1. ‘Where the statute of limitation accrues between the date of filing and the date of service, whether or not it relates back (if the service is more than five days after the filing) depends on the length of time and the diligence used by the plaintiff. The correct test must be whether the plaintiff showed that he acted in a reasonable and diligent manner in attempting to insure that a proper service was made as quickly as possible. A reasonable rule must be that in such case the trial judge should look at all the facts involved and ascertain whether the plaintiff was in any way guilty of laches. If he were, of course he would be barred, but if he acted in a reasonably diligent manner then he would not be. The plaintiff has the burden of showing lack of fault. . . . The question on appeal is whether the trial court abused its discretion in concluding that there was [not] due diligence by plaintiff in seeking to perfect service. To reverse the trial court, we would have to say as a matter of law that the trial court abused its discretion.”2
*766“The special duty the plaintiff bears to exercise reasonable diligence in serving a complaint for which the statute of limitations has expired, is too well established to dissertate. [Cits.] The thing that can never be lost in sight is that the plaintiff’s cause of action was dead. It could not be revived unless the plaintiff used due diligence to perfect service, which diligence must be examined in light of the particular fact that the cause of action had expired.”3
Diligence means “caution or care; persevering application: devoted and painstaking application to accomplish an undertaking: assiduity.” Webster’s Third New International Dictionary. It embraces the concept of persistence. We must remember that when measuring diligence with respect to service of process, it is in the context of notifying a defendant of suit beyond the time the law ordinarily allows for the bringing of such a suit. It is the plaintiff’s grace period.
This “special” duty of due diligence is elevated to an even higher duty of the greatest possible diligence once plaintiff becomes aware there is a problem with service. If the sheriff returns the summons after failed attempts, plaintiff becomes “ ‘obligated to exercise, not due diligence, but the greatest possible diligence to ensure proper and timely service.’ [Cit.]”4 At that point “reasonable diligence” is insufficient.5 The same elevated duty arises when defendant’s answer challenges service.6
On August 11 Wade sent the summons and complaint to the sheriff to serve Dr. Whalen at a residence in Cobb County, Georgia. Dr. Whalen had moved to Irving, Texas, seven months earlier. The sheriff returned the service form to Wade by August 30 and indicated the doctor had moved. Wade sent the complaint via certified mail, return receipt requested, to the Cobb County address. It was forwarded to Dr. Whalen in Irving where he signed the postcard evidencing receipt. When Wade received the postcard, he sent another copy of the summons and complaint to the Cobb County sheriff and *767requested service be reattempted.
On October 12 Wade received Dr. Whalen’s answer, which raised the defenses of defective service and statute of limitation and which denied he resided at the Cobb County address. Wade hired a private investigator on October 18, who informed Wade the next day of the doctor’s address in Irving. A week later Wade served interrogatories asking for the doctor’s current home address and place of employment.
Sometime between November 10 and 17 the Cobb County sheriff returned to Wade the service form showing unsuccessful service. Wade forwarded process to a Texas constable in Irving on the latter date. On December 1 Wade received Dr. Whalen’s interrogatory responses which confirmed the Irving address and specified a work address. Two weeks later Dr. Whalen moved to a new residence in Dallas and on December 31 completed his work assignment for that employer. Service was unsuccessful at either the Irving address or the work address, and on January 12 Wade received the summons and complaint back from the Texas constable.
Several weeks later (February 3) Wade sent a letter to Dr. Whalen asking him to acknowledge service. The doctor moved for summary judgment on February 15 and served an affidavit listing his new address in Dallas. Wade forwarded the summons and complaint on March 14 to a Dallas constable, who in turn phoned Dr. Whalen on April 3 and 4 and set an appointment and served him on April 10.
During the eight months between the filing of the complaint and service of process, Wade was directly responsible for four significant delays. First, between August 30 and October 17 (47 days) Wade made no substantive effort to determine Dr. Whalen’s correct address even though (i) by August 30 the Cobb County sheriff had returned the service form indicating Dr. Whalen had moved and (ii) on October 12 Wade had received the doctor’s answer asserting defective service and denying the Cobb County address.7
Second, from October 19 through November 16 (28 days) Wade was aware from his own investigator that the doctor had moved to Irving, but did not forward the process papers to an Irving constable until November 17.8
Third, from January 12 through February 2 (21 days) Wade did nothing to pursue service even though on January 12 he received the *768summons and complaint back from the Irving constable.9
Fourth, from February 16 through March 13 (25 days) Wade did nothing to pursue service even though (i) he was aware of Dr. Whalen’s new Dallas address and (ii) Dr. Whalen sought summary judgment based on ineffective service.10
Wade made at least three errors contributing to the delay in service. First, he provided the Cobb County sheriff with an address that was seven months outdated, even though Dr. Whalen’s forwarding address was available from the post office. “The burden is on the plaintiff to ascertain a defendant’s residence, and that obligation does not arise only upon expiration of the statute of limitation. [Cit.]”11 Plaintiff is obligated to ascertain this information before filing suit.12
Second, Wade sent a certified letter to the Cobb County address “in an attempt to see if the United States Post Office would disclose a new address.” He did not check the box on the certified letter form (for an additional fee) to receive the addressee’s forwarding address. The letter was forwarded to Whalen’s Irving address where he signed the postcard that was returned to Wade. Not having been requested nor paid to do so, the postal service did not alert Wade to the Irving address. Wade’s conclusion that this meant Dr. Whalen still lived at the Cobb County address was simply his own mistake that delayed discovery of the correct address.
Third, Wade misled the Irving constable by telling him Dr. Whalen traveled frequently to Atlanta and that he should try to serve him on a weekend. Dr. Whalen testified without contradiction that he traveled infrequently to Atlanta and never on a business day. The weekends were the least likely time for him to be home.
Based on Wade’s delays and missteps, the court did not abuse its discretion in finding Wade did not show the greatest possible diligence.
2. Citing OCGÁ § 9-11-26 (e) (2) (B), Wade contends Dr. Whalen was obligated to supplement his interrogatory responses to indicate that two weeks after serving them he moved to the new Dallas *769address. Regardless of whether the statute applies to this interrogatory response and whether Dr. Whalen’s February affidavit was a “seasonable” amendment under the statute, the two-month period between Dr. Whalen’s relocation and the affidavit overlaps only one of the four significant delays caused by Wade and does not excuse any of his three additional errors. Adequate other evidence grounded the court’s finding.
3. Citing Starr v. Wimbush,13 Wade argues that the first two orders of the court denying the motion for summary judgment and specifically finding ample evidence of reasonable diligence precluded a contrary later finding. The first order was entered on March 24, 1995 (before service was effected), and the second order was entered on September 21, 1995 (after service was effected).
In Starr the trial court had ordered service by publication in a ruling expressly finding defendant could not be found after due diligence.14 Defendant was personally served two months later, during which time several additional steps were taken to locate him. Because the attempted service by publication was ineffective, and because service had not been perfected until eight months after the statute of limitation had run, defendant moved to dismiss. The court granted the motion, finding plaintiff had failed to show due diligence in attempting to perfect service. Starr reversed, holding the publication order had established due diligence and the record clearly showed due diligence from the time of that order until service.
Starr is reconcilable with OCGA § 9-11-60 (h), which in 1966 (amended in 1967) abolished the law of the case rule.15 Nevertheless, “judgments and orders shall not be set aside or modified without just cause and, in setting aside or otherwise modifying judgments and orders, the court shall consider whether rights have vested thereunder and whether or not innocent parties would be injured thereby. . . .”16
Summary judgment orders which do not dispose of the entire case are considered interlocutory and remain within the breast of the court until final judgment is entered.17 They “are subject to revision at any time before final judgment unless the court issues an order ‘upon express direction’ under OCGA § 9-11-54 (b).”18 Because no express direction was issued on the first two orders, and because no *770rights had vested nor would any innocent parties be injured, power remained to revise the previous summary judgment orders upon a showing of just cause, an ingredient not demonstrated in Starr.
In Wade’s case, the previous orders applied a standard of reasonable diligence whereas the greatest possible diligence was called for.19 Both previous orders had been entered without a hearing, even though hearings had been requested.20 Service did not occur until 17 days after the first order was entered. The judge who entered the second and third orders (another judge entered the first order) conceded that in entering the second order he had felt obliged to “parrot” the first judge without reviewing the matter closely. Unlike the first and second orders, the third sets forth a detailed analysis of the facts, including the ease with which service was perfected once a phone call was made to the doctor at his correct address. Modification of previous orders can be accomplished implicitly.21
4. Citing Poloney v. Tambrands, Inc.,22 Wade contends the doctor’s actual notice of the action as evidenced by his filing an answer and participating in discovery means he was not prejudiced by late service. “Such notice is irrelevant. Where there has been no service of a suit, or waiver thereof, the necessity of service is not dispensed with by the mere fact that the defendant may in some way learn of the filing of the suit. In this case, there was no timely service and there was no waiver thereof.”23 Poloney differs in that it lists reasons to uphold the trial court’s finding of diligence; such rationale has been rejected as a basis to reverse a trial court’s finding of lack of diligence.24
Judgment affirmed.
Ruffin, J., concurs. Pope, P. J., concurs specially.OCGA § 9-3-71 (a).
(Citations and punctuation omitted.) Siler v. Johns, 173 Ga. App. 692, 693 (327 SE2d 810) (1985); Alexander v. Searcy, 204 Ga. App. 454, 457 (419 SE2d 738) (1992) (determination of due diligence reversible if discretion abused and insupportable as matter of law). See Lawrence v. Noltimier, 213 Ga. App. 628 (445 SE2d 378) (1994) (judge must “ascertain whether the plaintiff was in any way guilty of laches”); see also Mitchell v. Hamilton, 228 Ga. App. 850 (1) (493 SE2d 41) (1997) (“ ‘plaintiff has the burden of showing that due dili*766gence was exercised’ ”); Cantin v. Justice, 224 Ga. App. 195, 196 (480 SE2d 250) (1997) (determination is within the trial court’s discretion).
(Emphasis in original.) Varricchio v. Johnson, 188 Ga. App. 144, 145 (372 SE2d 455) (1988).
Mitchell, supra, 228 Ga. App. at 851 (1); see Walker v. Bord, 225 Ga. App. 242, 243 (483 SE2d 675) (1997) (duty heightened to the greatest possible diligence once marshal returns summons).
Sykes v. Springer, 220 Ga. App. 388, 390 (2) (469 SE2d 472) (1996); cf. Ga. Farm &c. Ins. Co. v. Kilgore, 265 Ga. 836, 837 (462 SE2d 713) (1995) (“In determining whether diligence was exercised, the focus is upon the plaintiff’s efforts after becoming aware that the process server failed to perfect service in accordance with the time limit provided in OCGA § 9-11-4 (c)”).
Patterson v. Johnson, 226 Ga. App. 396, 398 (486 SE2d 660) (1997); Robinson v. Stuck, 194 Ga. App. 311, 312 (1) (390 SE2d 603) (1990); Roberts v. Bienert, 183 Ga. App. 751, 752 (1) (360 SE2d 25) (1987).
See Devoe v. Callis, 212 Ga. App. 618, 620 (1) (442 SE2d 765) (1994) (“the record shows an unexplained lapse of over a month ... in which there was no effort by [plaintiff] to verify [defendant’s] address”).
Id. (“After the private investigator discovered that [defendant] had moved, there was an additional delay of nine days before [plaintiff] contacted a process server”).
See Walker v. Bord, supra, 225 Ga. App. at 243 (plaintiff “did nothing for ten days following his failed attempt at serving” defendant); Varricchio, supra, 188 Ga. App. at 145 (“plaintiff sat and did nothing” to attempt service for over three weeks after sheriff informed plaintiff that defendant had moved).
Devoe, supra, 212 Ga. App. at 620 (1) (plaintiff “did not act promptly on new information”).
Id. at 619 (1) (defendant had moved eight months before plaintiff filed suit); see Mitchell, supra, 228 Ga. App. at 851 (1) (address was two years old); Patterson, supra, 226 Ga. App. at 398 (plaintiff has “the responsibility to investigate and learn where the defendant may be located and served”); Walker v. Bord, supra, 225 Ga. App. at 242 (forwarding address was available from post office).
Walker v. Hoover, 191 Ga. App. 859, 861 (383 SE2d 208) (1989).
201 Ga. App. 280, 281-282 (2) (410 SE2d 776) (1991).
Id. at 282.
Ga. L. 1966, p. 664, § 60 (h); Ga. L. 1967, p. 239, § 27.
OCGA § 9-11-60 (h).
Hodges Plumbing &c. Co. v. ITT Grinnell Co., 179 Ga. App. 521, 522 (1) (347 SE2d 257) (1986); see Barber v. Collins, 201 Ga. App. 104, 105 (2) (410 SE2d 444) (1991).
Hodges, supra, 179 Ga. App. at 522; see Bradley v. Tattnall Bank, 170 Ga. App. 821, 822-824 (1) (318 SE2d 657) (1984).
See Sykes, supra, 220 Ga. App. at 390 (2).
Because the requests were not contained in a separately filed pleading entitled “Request for Oral Hearing,” the court was not required to hold a hearing but could do so at its option. See Uniform Superior Court Rule 6.3.
Glover v. J. C. Penney &c. Ins. Co., 181 Ga. App. 753, 754 (1) (353 SE2d 587) (1987).
260 Ga. 850, 852 (2) (399 SE2d 208) (1991).
(Citations and punctuation omitted.) Walker v. Bord, supra, 225 Ga. App. at 244; see Sykes, supra, 220 Ga. App. at 390 (3).
See Walker v. Bord, supra; Sykes, supra.