Where an agreement has been entered into in terms of section thirty-six providing that no action shall be taken in terms of section thirty-five—
(a) for twenty-five years, no compensation shall be payable by the local planning authority; or
(b) for a period of less than twenty-five years, the agreement may provide for a reduction in the amount of compensation payable by the local planning authority;
in respect of any action taken in terms of section thirty-five at or after the expiration of that period.