I recently had my air conditioner at home begin not working properly so I called Frigidaire because my manual said it was covered by a seven year warranty. They scheduled a service, and the guy came out and fixed our ac in a few days. We signed no papers, and he specifically said we owed him nothing. Now he is calling saying we owe him money. Frigidaire is now saying the unit is not under warranty. Are we legally liable to pay now?