They ripping me off.. and i have evidence

i buy a car on auction, based on dekra report they provided. i get to the car, driver door not locking, boot shocks finished and not reported. thats fine I say. i test drive the car, Gearbox fails. on dekra report, Gearbox is very good. I refuse the car because i would not have bidded for it if gearbox problems were reported. now thye refuse to give me my money back. 124.5 K. they say i must call customer care. i need advice please