Air Conditioner problems of the 2018 Chevrolet Traverse

Purchased a 2018 Chevrolet Traverse in October. Beginning within the first 30 days the car made a loud roaring noise when @ 2100 rpm and going approximately 74 mph. Just thought it was a fluke. Then starting in December, while travelling out of town, it persisted every time we drove it. It also would lose power or something strange when putting it in gear after backing out of our driveway. We would accelerate for a short distance when the rpm's would rev-up to 6-7,000 rpm but the car wouldn't go. It was almost as if it would slip itself into neutral while going down the road. We have taken the car in 4 different times for repair and the problem has not been fixed. The car also turns itself off. The panel goes black. When we start hearing a loud rumbling noise while sitting in neutral at a fast food drive thru or red light we turn the air conditioning off to try and hear the noise better and the car dies and the panel goes black. We have had to actually re-start the car. We are extremely concerned for the safety of this vehicle and are returning it do the dealership tomorrow for our final time. They have been given numerous opportunities to repair the problem and things are actually getting worse. This is such a shame because we were so excited about our new car. We live on a very busy road where vehicles and 18 wheelers can go in excess of 70 miles an hour and I am afraid to pull out of my driveway with this car. We have even coasted to the side of the road when it looses power to avoid being hit from behind. The dealership wouldn't even start repairs until they could duplicate the problem. Finally a mechanic road with us and witnessed the noise but they have not been able to "duplicate" the slipping out of gear type problems. Since it is happening regularly now, maybe then can see for themselves. It has truly become a serious safety problem.