This case involves a claim for optional personal injury protection (PIP) benefits under a policy issued to Mullins by the First General Insurance Company (First General). The policy, which provided $5,000 in optional PIP benefits, became effective on October 19, 1982. Mullins was involved in an accident on January 6, 1983, after which he filed a claim for $50,000 in optional PIP coverage. His claim for additional PIP benefits was rejected, and he filed suit to collect the optional benefits, claiming that he was not given the requisite opportunity under OCGA § 33-34-5 as it existed before its amendment in 1982, Ga. L. 1982, p. 1234, to accept or reject those benefits. The trial court granted the defendants’ motion for summary judgment, and Mullins appealed to the Court of Appeals, which has certified the following question to this court: “Is the holder of a motor vehicle liability insurance policy in existence prior to November 1, 1982, whose application for insurance did not meet the requirements of OCGA § 33-34-5 (b) in effect prior to November 1, 1982, thereafter barred by the amended OCGA § 33-34-5 (c), which became effective on November 1, 1982, from the ‘right to demand and receive the benefit of $50,000 coverage upon tender by the insured of such additional premium as may be due and filing of proof of loss ...?’”
OCGA § 33-34-5 (c), as amended on November 1, 1982, provides that “[a]ll named insureds in motor vehicle liability policies in effect *487on November 1, 1982, shall be deemed to have signed the statement required by subsection (b) of this Code section.”
The initial issue here concerns the effect of the amendment of OCGA § 33-34-5 (c). In construing a statute a primary rule is that the courts must try to ascertain the purpose and intent of the legislature and then try to construe the law to implement that intent. Hollowell v. Jove, 247 Ga. 678, 681 (279 SE2d 430) (1981); Wilson v. Board of Regents, 246 Ga. 649, 650 (272 SE2d 496) (1980). It is also fundamental that when a statute “ ‘is plain and susceptible of but one natural and reasonable construction, the court has no authority to place a different construction upon it, but must construe it according to its terms.’ ” Hollowell v. Jove, supra, 247 Ga. at 681. Moreover, “[i]t is presumed that all statutes are enacted by the General Assembly with full knowledge of the existing law, including decisions of the courts.” Medical Center Hosp. Auth. v. Andrews, 250 Ga. 424, 426 (297 SE2d 28) (1982). Accord Price v. City of Snellville, 253 Ga. 166, 167-168 (317 SE2d 834) (1984).
At the time of the amendment of OCGA § 33-34-5, an insurance company’s failure to comply with the requirements of former OCGA § 33-34-5 (b) meant that the insured was entitled “to demand and receive the benefit of $50,000 coverage. . . .” Flewellen v. Atlanta Cas. Co., 250 Ga. 709 (1) (300 SE2d 673) (1983). In light of the clear language of the November 1, 1982 amendment, we must conclude that the General Assembly took cognizance of its prior enactment and the case law construing it, and that its purpose was to alter the law in order to bar claims for optional PIP benefits by insureds who held policies existing as of November 1, 1982 which were not in compliance with former OCGA § 33-34-5 (b). See Price v. City of Snellville, supra, 253 Ga. at 168.
In order to fully answer the Court of Appeals’ question, our finding as to the General Assembly’s intent in enacting amended OCGA § 33- 34-5 (c) necessitates the determination of an important related issue: is an insured, whose policy was not in compliance with former OCGA § 33-34-5 (b), now barred from bringing a claim for optional PIP benefits, if the claim stems from an accident occurring before November 1, 1982? Because such an insured’s claim for optional PIP benefits would have accrued on the date of the accident, OCGA § 33-34- 5 (c), as amended, cannot be applied retroactively to defeat that claim. See Enger v. Erwin, 245 Ga. 753 (267 SE2d 25) (1980). Thus, as for accidents occurring before November 1, 1982, the Court of Appeals’ question is answered in the negative.
In the present case, however, Mullins’ accident occurred after the November 1, 1982 amendment of OCGA § 33-34-5 (c), and we find no reason which prohibits that amendment from barring him from “demanding] and receiving] the benefit of $50,000 coverage. . . .” *488Flewellen v. Atlanta Cas. Co., supra, 250 Ga. at 712. We find no merit to appellant’s argument that based on our decision in Flewellen he acquired a vested contractual right to $50,000 in PIP coverage, and that amended OCGA § 33-34-5 (c) therefore cannot bar his action. This argument is based on the theory that in Flewellen this court grafted $50,000 in PIP coverage into all non-complying insurance policies when it stated that “[i]n the absence of such a rejection, the policy . . . provides $50,000 PIP coverage from its inception.” Flewellen v. Atlanta Cas. Co., supra, 250 Ga. at 712. We reject this argument because Flewellen merely created a remedy for a violation of OCGA § 33-34-5, not an implied substantive contractual right.
Decided November 6, 1984. Hardigg & Hardigg, James A. Hardigg, for appellant. Dennis, Corry, Webb, Carlock & Williams, Thomas S. Carlock, R. Clay Porter, Conrad & Abernathy, Philip C. Smith, for appellees. Allman & Banner, Douglas F. Aholt, amicus curiae.The appellant also argues that at the time he entered into the insurance policy with First General he had a vested right under former OCGA § 33-34-5 (b) to have his acceptance or rejection of optional coverage accompanied by his signature. He contends, therefore, that amended OCGA § 33-34-5 (c) cannot impair that right. We disagree. That signature requirement was a procedure to be followed to indicate the acceptance or rejection of optional coverages, and was thus not a vested right. See Armistead v. Cherokee County School District, 144 Ga. App. 178 (3) (241 SE2d 19) (1977); Bullard v. Holman, 184 Ga. 788 (2) (193 SE 586) (1937). Thus, as for accidents occurring after November 1, 1982, the Court of Appeals’ question is answered in the affirmative.
Certified question answered.
All the Justices concur, except Hill, C. J, who concurs specially and Clarke, Smith, and Gregory, JJ., who dissent.