My BMW dealer and I agreed to a part exchange over the phone for my X3 against a one year old car they were offering for sale. The order paper was sent by email, but before I could return it, another salesman then emailed me within 24 hours to say that the car was no longer for sale and had been transferred to another dealer. The dealer is allegedly going to return my deposit, paid four days ago, of £1000 as soon as possible. But having agreed to the part exchange and having taken the money, what are my legal rights? It was a good deal and I'm disappointed not to complete the purchase.