Previous Damage
 

I bought a 2011 Q7 from a Connecticut Audi Dealer about three years ago. Recently I've notice a crack in the rear driver's side door. I took it to an auto body shop for advice, and they said that the entire side of the door had been damaged and repainted. I bought this certified used and was made aware that it had been damaged. Contacted the dealer and they refused to do anything. What can I do now?