How to get my money back that was promised 4 months ago

Bought a piece of heavy equipment from a dealer over the phone. I had been looking for some time, when I saw his add for a low hour machine in very nice shape. I purchased it and paid a transport company to deliver it. I received it on a Sunday and immediately saw this machine was not in the shape that the dealer had stated. I called the dealer the next morning and expressed my concerns. He said he would refund my money. It has been 4 months and he has not paid me yet. He always has some kind of excuse. What can I do?