During recent heavy rains, all of a sudden the car's transmission that had been working fine, after having been parked briefly pointing slightly down hill, no longer functioned properly, and had apparently gone into "LIMP Mode". after talking with Mechanics and doing research, we checked the carpet areas and determined and documented the car's interior was very wet, both in front and in the rear areas, with evident moisture and corrosion under the battery and cabin air filter areas and rear wheel well area. The Transmission no longer shifts properly and the car is not able to be safely driven. Apparently there is a well known design flaw in the Audi C5 A6 vehicles where multiple drains frequently fail. apparently there are 2 very hard to access drains under the battery, under the battery tray, and also the cabin air filter seal to the sidewall is prone to failure. I'm told that there is a "soft" NTSB Audi Recall on this. Please advise.

- Fairfax, CA, USA