I would go and talk to a lawyer just to get an idea of what legal rights you have and what they think you should get out of the dealership for having to deal with this crap. Most lawyers will give you a couple minutes worth of advise over the phone (at least in my area) to give you a general idea of your rights. They might suggest you stop in and speak with them in detail about the situation. I wouldn't hesitate to go in and talk, always better to be fully informed of what you can get for your troubles than to be talked into taking crap from the dealer.
Once you know what you are up against, I would have a long sit down with the owner of the dealership to give him a chance to fully rectify the situation. Inform him you have spoken with a lawyer and you know your rights from the get-go, just so he knows you came to the party armed and won't try to screw you over.
Sorry for your troubles.