Similar thing happened to us a few years ago on a new TT. We put a $5000 down payment on a TT. They were slow on calling us back about financing. Called them and they said they didn't have our right number. That was false as they had our home and both Purcell phones. Any way they said I needed to call some lady with a finance company they used. They didn't even have a finance person of their own! Called and she tried to give me some ridiculous rate like you got. Maybe even higher. We said no. She had us thinking our credit was terrible. I called the dealership back and to,d them it was a no go and they sent our check back.
I believe that the deal is contingent upon financing. At least that is how it's always worked for us. Even when purchasing our mh recently we only gave a $200 hold. It was refundable.
I would talk to the dealership and tell them as a couple others said, it's not going to work due to the high interest rate that you were given. I don't think there is any need to talk to a lawyer right now. You need to try to handle it yourself with the dealer. You haven't accepted the rv yet after all.
