2020 BUICK ENCLAVE Vehicle Speed Control Problems

I BOUGHT A 2020 BUICK ENCLAVE, (OWNED BY GMC) WITH 6 MILES ON IT, 1 WEEK AGO. YESTERDAY THE CHECK ENGINE LIGHT CAME ON AND THE CAR STARTED JERKING ANYTIME THE TRANSMISSION SWITCHED GEARS. I CALLED TO TRY TO GET IT IN TO A CERTIFIED BUICK DEALERSHIP TO BE LOOKED AT AND NOWHERE CAN GET IT IN FOR 3-5 DAYS AND NONE OF THE DEALERSHIPS WILL GIVE A LOANER CAR UNTIL THE TIME OF THE VEHICLE APPOINTMENT. I CONTACTED BUICK DIRECTLY REGARDING THIS AND THEY TOLD ME THE SAME THING, THAT WE CAN'T GET A SAFE DRIVING VEHICLE, UNTIL THE ONE WE HAVE CAN BE LOOKED AT BY A DEALERSHIP AND IF WE TAKE IT TO AN UN-CERTIFIED SHOP THAT IT WOULD NOT BE COVERED. SO NOW I AM STUCK WITH EITHER DRIVING AN UNSAFE CAR 50 MILES ON THE HIGHWAY TO WORK FOR THE NEXT FEW DAYS OR NOT...