Rear Seat Belt problems of the 1998 Mazda 626

The webbing has started to separate on the passenger rear seat belt and is about half way across (the width) of the seat belt. The dealer states the belt has been cut. The belt has not been cut. I have contacted Mazda and can talk to no one other than the person at the other end of the 800 number. That person (have talked to two diff. People on two diff. Occasions) tells me the dealer is the eyes and ears of Mazda and that they have the final say. Help!!.