There is a caveat here, I think.
Any hours flown in a SEP(A) towards the issue of a PPL SEP(A) count in full. I don't think these hours expire, like your exams do.
But hours flown in a helicopter, TMG, Microlight, glider or any other non-SEP(A) type will only count to a certain extent. Details in LASORS, as usual.
Twistedenginestarter, was this what happened in your case?