maybe offer the dealer a non confrontational way out. praps if he gives you back what you paid for the car, with £250 to cover out of pocket expenses (private plate transfer etc), with no vosa, trading standards etc.
one of the first things I was taught about negotiating was always offer a solution or way for the other party to back down with losing face.
Surely without losing face would be better?
I take it yu didnt get far on that course?