Brake Sensor problems of the 2018 Audi Q5

Twice in 2019 my car slammed to a stop while backing up at 2-3 mph. I had not hit anything and no damage to car. There was nothing to hit, just a vacant area. Yesterday while driving forward at 35-40 mph on a main street with the closest oncoming car 1 block away my car slammed to a dead, wall slamming stop. If a car had been behind me there would have been an accident. I emphasize: this was a dead, no slow-down stop. I refused to drive it 50 miles to the dealer. The dealer has picked it up and told me the sensors were set too sensitive. If so, why did this not occur every time I drove? frankly, I am afraid I will be forced to drive this car for the next 3 months until my lease expires. The dealer will not give me a loaner. I think this is a very unsafe car. I have no confidence in the way this is being handled. For your interest, I was given a ride today in the 2019 sedan model. Unbelievably it slammed to a stop while backing out of my driveway.