Transmission Not Go Into Gear problems of the 2016 Chrysler 300

I rented a car from fox car rental and I was renting 2016 Chrysler 300 my dream car has I was driving turned right on a residential street the rear shift by it self the nob turned when I pressed on the breaks I got real scared and I went back to the car rental and told the manger that this car that is a 2016 car they just received needed to be returned to the dealer cause it malfunction when I press the breaks the nob of the 2016 Chrysler 300 gear shift changed gear on its own. I was only going 5mph that is very dangerous especially if you are driving in a down stiff road or street I do not think the nob gear does not lock so it changed rear on its own when you do a sudden break.