2011 BMW 5 SERIES Seats Problems

WHILE DRIVING FOR 15 MINUTES WITH SEAT WARMERS ON MY HUSBAND (DRIVER) TURNED IT OFF. WE WERE TRAVELLING ON SUBURBAN ROADS AROUND 40 MPH. THEN AT A STOP LIGHT HE NOTICED A BURNING SMELL. WE CONTINUED DRIVING WHEN LIGHT TURNED GREEN. THEN I NOTICED THE SMELL A FEW SECONDS LATER, SO I OPENED A WINDOW EXPECTING TO FIND SMELL A FIRE NEARBY OR HEAR SIRENS. AT THAT POINT WE SAW A PLOOM OF SMOKE COME FROM UNDER HIS SEAT TOWARDS THE PASSENGER SIDE OPEN WINDOW. HE IMMEDIATELY PULLED OVER, JUMPED OUT OF THE CAR AND TURNED EVERYTHING OFF. THE SMOKE TOOK SOME TIME TO CLEAR BUT DID STOP. SEVERAL MINUTES LATER WE DROVE 1 MILE TO THE BMW DEALERSHIP. WE WERE TOLD ITS NOT UNDER WARRANTY, AND WOULD COST $1,700 TO FIX. I DECLINED TO PAY $1,700 TO FIX AND REQUESTED THEY DISCONNECT SEAT HEATER. BMW PERSONNEL INFORMED ME IT...