2001 Audi S4 Air Bags & Restraints Problems

I took the vehicle into the dealer (Westwood Audi) for a Safety Recall repair as requested by Audi. It was for a Driver Front Airbag Inflator replacement. The work was done but when the car was returned the airbag warning light was on. I went back in to the service department and was told that the airbag module had failed and that the part was no longer available from Audi. An aftermarket part could be installed but I would have to pay for part and the repair. No cost estimate has been given. I called Audi of America and they said that the Dealer told them that they didn't break it so they will not cover the cost of repair. I have owned this car for 20 years and it is in exceptional condition. I took it to the Dealer in perfect condition for an airbag repair and got it back with an air bag warning light on and they say they didn't do it? Now I have a car without functioning airbags. Anything that you can do to help resolve this?

COLD START ON A COLD JANUARY MORNING (5 DEGREES F); UPON STARTING THE CAR THE AIR BAG WARNING LIGHT CAME ON AND WOULD NOT SHUT OFF. RESEARCH (DISCUSSIONS WITH THE DEALER AND AIR BAG REPAIR BUSINESSES) INDICATE THAT THIS IS A VERY COMMON DEFECT FOR AUDI S4, MODEL YEAR 2001 AND THAT TO REPAIR THE PROBLEM THE AIR BAG CONTROL MODULE (COMPUTER) WOULD NEED TO BE REPLACED AT AN EXORBITANT COST. AIRBAG SYSTEM IS COMPLETELY INOPERABLE WITH THE WARNING LIGHT IN A LIT STATE. ON LINE AUDI FORUMS INDICATE THAT THIS IS A HUGE PROBLEM ON THESE CARS. *TR

DT: SEAT BELT DOES NOT INSERT PROPERLY INTO DRIVER'S SIDE BUCKLE. CONSUMER COMPLAINED TO DEALERSHIP MULTIPLE TIMES. THE SEAT BELT HAS RELEASED WHILE CONSUMER WAS DRIVING.*AK