cheated $3,000

[r_e_mendez]

What is the name of your state? texas
What is the name of your state? texas

a little more than a month ago my boyfriend bought a car from a dealership...it was a 2002 mercury sable and we paid 8,000 for it...we signed all the papers and everything was set. well, the man that had sold it to us (let us call him "david") called us around 4 days later and said that the previous owner of the sable wanted his car back because he couldn't get financed for a new car. so my boyfriend took the car back and david showed him another car, a 1998 chrysler sebring. my boyfried asked how much this car was and david said that he could give it to him for 8,000, the same price as the other car. well, all the paperwork was done again for this different car. (the bumper was damaged and we have a document that states that they "owe" us work on the bumber to fix it).
so my boyfriend gets home and goes on line and finds out that this same car, with the same VIN # from the dealership website is being sold at $5,000. we go back the next day and confront david about. he (of course) pretends he didn't know that it was 5,000. apologizes and says that with the body work that they were going to do, it was going to end up being 8,000. we decide that we don't want the body work and we just want the car as is. at this point they still need to fix the brakes and do the safety check, so david agrees that he was going to reimburse the rest of the money after the safety check and the brakes. he also said that the taxes alone was going to be $500, so the car in reality after taxes was 5,500. we take the car to get the safetly check and the brakes. when we pick it up, he states that he got other things fixed on the car and that it turns out to be close to 8,000 anyways. it's been a month and he still hasn't provided us with an invoice to the "work" done to the car and we haven't seen any reimbursments. my boyfriend showed up today and talked to a manager, and this guy just told him that they don't do reimbursments and the best he can do is give him a full tank of gas. we've called david 4 times today and he is not returning our calls and avoiding us when he does answer telling us that he'll call back.
any advice on our rights at this point?