Refunding my Down Payment

[olson.tc]

I recently bought a new car from a dealership. I found a car I liked, test drove it twice and on the second test drive the service engine light came on. Come to find out the transmission went out. I then found another vehicle on the same lot and proceeded to put a $4000 down payment on it. I was supposed to pick the vehicle up on a Saturday but ended having to go out of town and told them I would be back on Monday to pick the vehicle up, they said it was alright with them and they would have it all washed and ready to go for me on Monday. I returned to the dealership on Monday and they informed me that they had sold it, in return they said I could pick any car off of the lot until they found me a matching vehicle to the one that they had sold under me. I ended up liking the vehicle i had pick off the lot and continued to by the car. having the car now for two weeks I have come to find out that my girlfriend is pregnant and that the 2 door convertible is not a very family friendly vehicle. At this specific dealership they have a 30 day exchange policy on all of there vehicles. I called my dealer and asked him if i could simply get my $4000 down payment back or atleast some of it because I did drive the vehicle for two weeks. He furthered to tell me that he couldn't give the money back but would talk to his boss to see if he could. Do I have legal rights to get my money back, or does the dealer get to keep all of my money that I put for a down payment? Whats the deal?