Transmission Failure problems of the 2013 Audi S4

The problems started by a warning on my display saying to pull over gear box or transmission failure. You have seconds to pull over before the car no longer functions. Even though you are in gear all that happens is the engine revs and you go no where. My car has only 38,500 miles on it and is out of warranty by a couple of months. I had the car tuned adding somewhere around 100 hp 6,000 miles before this happened and Audi says this is what caused the issue. To fix the sensor error code p179e00 was around $5,000. 00 even though there has been a service bulletin out for this problem for more than a year. After looking around decided to have Audi do the repair but within an hour of letting them know to go ahead with repairs they called me back and told me that it could be the whole transmission when they tested the fluid it came back with some metal shaving in it. This would be a $12,000. 00 repair. The safety of this transmission is in question for the fact that there has been a service bulletin out for this transmission even though Audi of America denies that my VIN is part of the service recall. It is pretty scary when you driving and the transmission just shuts down and you and you car are just stuck in traffic as cars Dodge you and fly by you and you dead car.