AUDI HEADACHES

My 2002 Audi A-6 3.0 took in a TON of water in a couple severe rain/
wind storms this past summer 2007.  I have had NOTHING BUT PROBLEMS
with it since.  My brake (re-call taken care of) booster was full of
water and the brakes FROZE on the road on a trip.  Prior to that I've
been going around with a mis fire in the cylinder (per my local
mechanic) to the point it misfires so bad it is undriveable.  After
the brake deal and after they said my problem was I needed new tires
(which I now have) my check engine light is on again (less than a
week) from the 2nd. tow into Audi.  My belief after much research is
that it is catalytic converter issues. Possibly from WATER as I cannot
stress to you enough HOW MUCH water this car took in - both engine and
interior of car.  I have YET to get Audi to direct themselves to the
fact that ALL the problems I have had with the car is since it took in
droves of water.  With the amount of money  $$$$ this car has cost me
I'm quite upset not to mention it is my only source of trans****tation
and since summer of 2007 it is not driveable more than it is!!!