The monthly amount of the retirement allowance for any member of Plan A shall consist of an amount equal to three percent of the member's final compensation multiplied by his years of creditable service, provided however, that:
(1) For any employee who was a member only of the supplemental plan prior to the revision date, the benefit earned for service credited prior to the revision date shall be determined on the basis of one percent of final compensation plus two dollars per month for each year of service credited prior to the revision date, and three percent of final compensation for each year of service credited after the revision date; and
(2) No benefits provided by this Section shall exceed one hundred percent of member's final salary or the final compensation whichever is the greater.
(3) Provided that no retired employee shall receive less in retirement payments than the amount of his accumulated contributions at the date of retirement. Any balance remaining to his credit upon the retiree's death shall be paid to his designated beneficiary or estate.