2013 BUICK VERANO Vehicle Speed Control Problems

ON 10/6/2020, I WAS RIDING AS THE FRONT PASSENGER IN OUR 2013 BUICK VERANO. WE WERE TRAVELING ON THE HIGHWAY (70 MPH) AND HIT A BUMP AT THE START OF A BRIDGE. A WARNING LIGHT ILLUMINATED, THE ENGINE RPM SUDDENLY INCREASED AS IF THE TRANSMISSION DOWNSHIFTED, THE CAR DECELERATED AND MY WIFE PULLED TO THE SHOULDER. WE STOPPED, CHECKED THE GEAR SHIFT AND IT WAS STILL IN DRIVE, THE WARNING LIGHT DISAPPEARED, AND EVERYTHING SEEMED NORMAL.

I WAS PARKING MY VERANO IN A FLAT PARKING SPACE (NO HILLS) ON DRY PAVEMENT. I WAS IN THE SPACE, I TOOK MY FOOT OFF THE ACCELERATOR AND STEPPED ON THE BRAKE TO PUT IT IN PARK, BUT BEFORE I COULD GET IT IN PARK, THE ENGINE REVVED UP, AND THE CAR TORPEDOED LIKE A ROCKET (VERY FAST) OVER THE PARKING BARRIER INTO A THREE OR FOUR FOOT DRAINAGE DITCH, WHICH STOPPED THE CAR FROM SHOOTING ACROSS ON-COMING TRAFFIC IN THE STREET. AS THE CAR JUMPED ACROSS THE PARKING BARRIER, I TRIED TO BRAKE AND THE CAR STILL WOULD NOT STOP. THE CAR ENDED UP FACE FIRST IN THE DITCH WITH DAMAGE TO THE FRONT END. I HAVE HAD THE DEALER EXAMINE THE CAR, BUT THEY FOUND NOTHING WRONG. I ALSO MADE A CLAIM TO GM AND THEY ARE INVESTIGATING THE SITUATION. SO FAR, I'VE BEEN RESEARCHING A FOUND A...