2018 Buick Enclave

MY CAR SHIFTS ITSELF INTO WHAT SEEMS TO BE A 'NEUTRAL' STATE AND THEN REVS UP VERY LOUD. IT ALSO SLAMS ON ITS OWN BRAKES, THANKFULLY EACH TIME HAS BEEN AT LOW SPEED. TODAY WAS THE LAST STRAW. I AM NEVER GETTING IN TO THAT CAR AGAIN! AS I WAS LEAVING A PARKING LOT, MY CAR SLAMMED ON ITS BRAKES, ALL KINDS OF ROLLING SOUNDS UNDER MY FEET. THEN IT STOPPED AND HIT HARD TO START GOING AGAIN. LIGHTS ON MY DASHBOARD GOING CRAZY... THE GUY WHO WAS BACKING UP AS I WAS GOING BY, HONKED AND YELLED AT ME BECAUSE HE DIDN'T KNOW WHY I WOULD STOP LIKE THAT. I SHOULD HAVE BEEN WELL PAST HIM, BUT MY CAR DECIDED WE WERE STOPPING. SO A LITTLE SHAKEN AND UPSET, BUT I CARRIED ON. THIS CAR HAS BEEN DOING THAT SINCE 4000 MILES. IT IS VERY STRESSFUL TO GET IN THAT CAR AS IT IS. I SAT AT THE VERY NEXT RED LIGHT AT THE PARKING LOT I HAD JUST LEFT TO TURN LEFT ONTO A MAJORLY BUSY STREET. THE LIGHT WAS RED, WHEN IT TURNED GREEN, I APPLIED THE GAS AFTER A AND IT SURGED SO HARD, IT WAS AS IF I FLOORED IT ALL THE WAY, BUT THE PEDAL HAD NOT MOVED UNDER MY FEET, BUT I COULD FEEL ALL KINDS OF 'ACTION' HAPPENING UNDER MY FEET. AS THE CAR WENT OVER THE CROSSWALK PAINT, IT SCREECHED THE TIRES AND I ALMOST HIT THE GUY WHO WAS ALSO MAKING A LEFT NEXT TO ME AS MY CAR WAS THRUSTING FORWARD WITH GREAT SPEED AND SPINNING TIRES, WHEN THE WHEELS CAUGHT THE PAVEMENT I ALMOST HIT THE GUY NEXT TO ME IN HIS BACK DOOR. I WAS HONKED AT AND SCARED. I WAIVED MY HANDS TO TRY TO SAY ' I DON'T KNOW!' I DIDN'T KNOW WHAT TO DO. THE MAN FOLLOWED ME ALMOST A MILE TO MY WORK AND WHEN I GOT OUT OF MY CAR HE CALLED ME EVERY NAME YOU CAN THINK OF. THIS CAR IS REALLY SCARING ME AND I CANNOT DRIVE IT ANYMORE. I AM GOING TO TRY TO WORK WITH GMC TO TAKE IT BACK. I SHOULDN'T HAVE TO BE TERRIFIED TO GO TO THE GROCERY STORE. THIS CAR HAS DONE SIMILAR THINGS OVER THE LAST TWO YEARS BUT IT HAS ONLY GOTTEN WORSE. DEALER "CAN'T DUPLICATE"