This looks like a horrible piece of shit and I can understand that you are feeling ripped off. Since the cars condition and the former representation are fundamentaly different I suspect this wasn't just a mistake, smells like fraud to me. I would contact the dealerships owner and kindly ask him to revert the deal. If he declines I would hire a good lawyer and discuss If it is a good idea to take this into the public.
A lesson I have learned is not to trust anyone I don't know personally on condition of things I buy. The more expensive they are the more a PPI is necessary. It is not funny to go through this lesson, but after all we always learn something and we never know what ist is good for. I am feeling for you and hope for a speedy and good outcome for you. Don't get too emotional, live is too short to waste time with negative emotions.