GYS PITZER MOTORS - no integrity!

When I bought a vehicle at Gys Pitzer motors I was very happy. BUT - BEWARE! I clearly recall asking him if the vehicle had been in an accident. The answer was a clear 'NO'. But now, on attempting to sell my car, every potential buyer has told me that this car has been in an accident. It was'nt since I purchased the vehicle, so it has to have been before! So my value automatically drops by R20 000. I know they won't respond to this, but would just like to let other potential buyers know so that they don't incur losses.