Excuses not to fix things under warranty

Ive sent in my son's ps3 to Cash Crusaders Brakpan which was still under warranty please bear in mind this was already a SECOND HAND product when we bought it from scratch the power button was like it was getting stuck until it finally broke we went to hand it in BECAUSE IT WAS UNDER WARRANTY just to receive a call to say they cant fix it it was us who broke it!!!!! Who the f@#$ are they to say we broke it do they have any evidence to state that we broke it as this playstation was not in use often. I will be taking this further!!!!