This also happened to my friend.
But my friend got them to retake the car. and this is how:

My friend said that she was not aware that this car was in a major accident and that if she knew it was in a major accident then she would NOT have bought it. The dealership can not accept a silent contract (meaning the dealer can't go ahead with the contract hoping that the buyer already knows this, it must be said or written so that the buyer is aware of this) and therefore legal actions can be brought down.

This was about 1.5 yrs ago .. I hope this helped you a little