Andrew,
Is there another Dealer in the area? If it was me, I would have that car, put on a tow truck, the kind you have them drive it up on, and get it out of that place.
I can't believe what they have done to you. Wondering what they do to other people's cars!
AND...Since they have had your car sooo long, and using it for "parts" for other people, I think I would go back to them, and TELL them, they better expedite your parts and get your car fixed! I would also make sure others in the dealership waiting for their cars could "HEAR what I was saying to them.
Cruiser
PS...I feel better now venting...on what I would do!