Dealer being a pain...HELP

[KittenRD]

Okay, I bought my car Thursday. I paid for it, signed all the paperwork, got the license plates (title in the mail), and I got my registration. With toyota, a new graduate can get $400 off. Since I am a new college graduate, I got the $400 off. The dealer said I only need to bring my diploma in to show them....so this is what I did. Problem is...my dad got a call the next day since I was at work (and I'm not allowed to have my cell phone on) from the dealer saying that this was only if you finance the car. He said that I need to pay them $400 or bring the car back. Help. I am not paying the $400 seeing I actually paid a little more than I should have. I am also not bringing my car back since I waited 4.5 months since they freakin lost my order or something. They are so incompetent! Never use Lexington Toyota. I could get the car I want from another dealer for cheaper, but then I'd have to wait about month and a half and I have my insurance all set up....