VEHICLE ROLLED BACK WHILE IN PARK. TRUCK WAS FOUND AGAINST THE HOUSE WITH THE DOORS LOCKED AND STILL IN PARK. EMERGENCY BRAKE IS TYPICALLY ENGAGED BECAUSE IT IS PARKED ON A SLOPE DRIVE BUT IT WAS FOUND DISENGAGED. WHILE BEING TOWED IT ALSO ROLLED WHILE LOADING ONTO THE TOW TRUCK. AGAIN, IT WAS IN PARK WITH THE EMERGENCY BRAKE ENGAGED. VEHICLE WAS LOOKED AT BY TWO SEPARATE SERVICE DEPARTMENTS WITH NO CAUSE FOUND. DAMAGE WAS DONE TO THE TRUCK AND THE HOME BUT SINCE GM COULD NOT DUPLICATE THE PROBLEM WE ARE RESPONSIBLE FOR ALL DAMAGES. WILL MOST LIKELY GET RID OF THE VEHICLE (TRADING IT IN AT SAME DEALER WHO SOLD AND SERVICED IT) BECAUSE WE DO NOT FEEL SAFE LEAVING THE VEHICLE UNATTENDED. TS