ON MARCH 16, 2017, I WAS TRAVELLING ON A MOUNTAIN HIGHWAY IN NORTHERN CALIFORNIA IN MY 2001 SUBURBAN WITH THE DRIVER'S SEAT HEATER ON. I WAS SITTING ON A THIN SEAT CUSHION. TWENTY MINUTES INTO THE 40 MINUTE TRIP, I TURNED MY SEAT HEATER OFF. TEN OR SO MINUTES LATER, I SMELLED A HORRIBLE RUBBER/PLASTIC BURNING SMELL. WHEN I REACHED MY DESTINATION, I LIFTED MY CUSHION AND SAW THAT THE SEAT HAD A BURNED HOLE THROUGH THE LEATHER AND INTO MY SEAT CUSHION. IT WAS WARM, BUT I DID NOT SEE A FLAME. WHEN I GOT HOME IN THE BAY AREA, I CONTACTED GM, AND THEY OPENED A CASE NUMBER AND TOLD ME TO TAKE MY VEHICLE TO A DEALER, AND THEY WOULD INVESTIGATE. I RECEIVED A CALL YESTERDAY FROM THE CUSTOMER SERVICE REP., AND SHE TOLD ME THAT THEY WOULD NOT BE COVERING THIS AS MY CAR WAS OUT OF WARRANTY, IN SO MANY WORDS. I ASKED WHAT THE DEALER HAD FOUND, AND SHE COULDN'T TELL ME. I REITERATED TO HER THAT THIS IS A SAFETY CONCERN FOR ME. MY PASSENGER SIDE SEAT HEATER IS NOW GETTING VERY HOT, AND I AM CONCERNED NOW ABOUT THAT. PLEASE NOTE, THE DRIVER'S SEAT HEATER IS STILL WORKING IF YOU ACCIDENTALLY HIT THE BUTTON ON THE DOOR. TODAY, I FOUND OUT FROM THE DEALER THAT THEY WERE NOT INSTRUCTED BY GM TO LOOK INTO THE SEAT TO SEE WHAT CAUSED THIS, ONLY TO TAKE PICTURES, ETC. NOBODY KNOWS WHY IT HAPPENED. HOW CAN THEY DENY ANYTHING WITHOUT DETERMINING THE CAUSE IS MY THOUGHT. AREN'T THEY CONCERNED THEIR SEATS OVERHEAT? SHOULD THEY BE WARNING THE PUBLIC? MY SEATS ARE IN VERY GOOD CONDITION