Transmission Gear Indicator problems of the 2009 Audi A3

I have an 2009 Audi A3 2. 0t with an automatic transmission. After about 20-30 minutes of driving the care the transmission starts exhibiting strange behavior. After coming to a full stop the car lurches forward after letting the foot off the brake. It makes a clunking sound and the gear indicator goes from the gear number displan to p-r-n-d indicator and then back to the gear number display. If you leave your foot off the brake, the car will repeatedly jerk forward. If you slowly accelerate the car is extremely jerky and not smooth like it should be. This makes for dangerous parking in a garage or where there are obstacles in the area. I am afraid to park it. The problem occurs everytime I drive the care for 20-30 minutes.