Air Bag Not Deploy problems of the 1999 Volkswagen New Beetle

Airbag light came on (has gone off and on for over a year); local mechanic unable to determine problem. 11. 09. 2005 took it to vw in brunswick, maine. Mechanic thinks there is a resistance issue and recommended replacement. He thinks it is a malfunction. The cost is over $500! I spoke to two CO-workers with different model vw's and had the same issue. Problem not resolved. Why should I pay for something that a mechanic thinks is wrong and others have to continuously pay for? if it is a defect then vw should be paying for it! my airbags have never deployed before. My car will not pass inspection with this light on.