Repair or replace car ?

Have the transmission serviced/oil changed by a repair shop familiar with Audi. Get them to a general inspection of the car and see what they think it would cost to get the car in top running condition and what they see as items to perform as preventative maintainence in the near or distant future. Look at www.kbb.com and see what your car is worth and weigh up what it would cost you to replace your car with a comparable car.

The car jerking around can be more than just the transmission. If you describe to me the problem in detail, maybe I can further assist you.