If the dealer's finance company won't approve the lease deal, the dealer hasn't received his money for the car, which means the car still belongs to him, regardless of documents you signed.This could be a scheme to get more money from you, but probably not. Most likely, the dealer simply was ignorant that the old promotional deal had expired. You could sue him for being stupid, but if the finance company won't approve the deal, you have the right to return the car.