Front Seat Belt Buckle Assembly problems of the 1998 Mazda 626

My husband noticed that the bolt holding the driver's side seat belt buckle was loose, so he attempted to tighten it. The bolt would not tighten, so my husband took the seat out to get to the bolt and the bolt just came right out of the housing unit without needing to unscrew it. The bolt was completely stripped and we cannot use the driver's side buckle now. I called Mazda headquarters and they said to take it to a dealership to diagnose the problem and it should be a free fix. I took it to the dealership and they said I was passed the 5 year, 60,000 mile safety warrantee and it wouldn't be free. To me, the seat belt should work no matter what, not be part of a warrantee of safety. I'm concerned because this may happen to others and in the event of a crash, the buckle may come out of the housing unit and render the seat belt useless.