Cant cancel ext. serv. contract-dealer will not return calls

We purchased a high end fifth wheel in June of 2016 from Camping World of Katy. All experiences have been pleasant with this dealership until July of 2017 when our fifth wheel caught on fire and was totaled by insurance. Luckily we purchased gap insurance at the time of purchase and also a good sam extended service contract. I have been trying to get this dealership to cancel my extended contract and they will not even answer the phone or call me back. The service contract must be cancelled before the gap insurance will pay off my loan. So I am still having to make payments because these scam artists will not cancel the contract. Buyer beware everything they do is to con you out of your money-absolutely no help for you after the purchase.