i would walk in there and demand satisfaction or threaten to sue him for not backing up his warranty, and call the bbb.
if he tells you to go f your self, go right to the court house and file a claim, its 25 bucks to do so, no lawyer needed. that notice he will get in the mail of being sued is usually more than enough in most case to fix your problem. these assholes like to play hard ball, play right back at them.
if your receipt says rebuild trans, you got him.