Check with insurance regulator as they may have some interest as well as the BBB.
There may be other regulatory agencies to wake up.
If you were told warranty via good sams get them on the phone as the dealer is using them as bait and switch and their legal guys may be able to do something.
Look at and pre sale notes or documents that may relate as one may have a pencil mark from sales guy stating the proposed deal.
Side note is if this place may be warranty authorized...
Contact the manufacturer of your mh even though you got used and not in warranty yiu ask if dealer is authorized to perform warranty work as you believe authorized places have better access to support etc.
If they are then have a conversation with service management.
There are lots of things you can do to make life more difficult for the dealer and in your conversations always have a solution available meaning what the dealer needs to do to make you happy.
Tony & Lori
1989 Country Coach Savannah SE