Car dealer says they lost the title to car I bought, now they want to sell

me somethin else, bait and switch? I bought a car from a used car dealership, signed the papers, got approved for the loan, got it insured, they told me to transfer my plates since everything was ready. I did this and when I came to the dealer to pick up the car, they told me they couldn't register it for me because they LOST the title. I think they are pulling a scam on me because in the last 2 weeks that I have been waiting for the title the guy has tried to sell me 3 different cars instead, and they all had problems. I WANT my car that I paid for (they cashed the check!). this is in MA, but the car is titled in NY. What legal recourse do I have? Can the dealer legally back out of the deal like that? I am so angry, I have already been waiting weeks for the car, and I transferred my plates already, so I had to rent a car just to drive to school. They never even took the car ad down from the website. They are claiming they ordered another title but I don't think its ever going to come. What do I do? the car is perfect, totally clean, no problems. I had it checked out by acura dealership. I will NOT accept a different car. please help!!