Noises During Shifting problems of the 2004 Audi TT

The first week of Dec 2014, I had been hearing a sporadic, whooting noise from the floor of my Audi Tt 2004 (49,000 miles). I brought my vehicle into the dealership on 12/05/14. Aside from some other non-critical repairs, the dealership could not find a cause for the noise and it was released. As I was driving the vehicle back to the dealership on 12/12/14 to pick up my other vehicle, I had significant issues. I was driving along north Ave at 35 - 40 mph in rush-hour traffic. As I was driving, the vehicle suddenly shifted into neutral and began to rapidly slow. In an effort to avoid a serious rear-end collision, I quickly engaged the hazard lights and slowed to a stop. Once stopped, I shifted into park (not certain if it actually shifted to park at this point), shut of the engine, and re-started. Fortunately, the vehicle made it safely to the dealership without another incident that day. The following week on 12/15/14, the dealer ran diagnostics on the vehicle. They noted a fault in the transmission, but could not determine the cause and after running 10 miles, noted that it was running well. In an effort to continue troubleshooting, the dealer used my vehicle to run errands. As they turned onto ogden Ave (westmont, IL), they had the same problem with the vehicle shifting spontaneously into neutral. I do not know the full details of that incident, but can imagine it was also a close call as ogden Ave is a busy, four-lane road. The official diagnosis was that it needs a mechatronics unit replacement. I am grateful that this incident did not happen on the highway and that I was not driving in front of a more aggressive driver (who may have otherwise collided with my vehicle). I believe this is a serious safety concern as it occurs while the vehicle is in motion, it occurs on a sporadic basis, and it is evidently undetectable at the dealership.