Front Air Bag Sensor Control problems of the 1998 Toyota Camry

When 98 Camry was first bought in sept 2000, I had a problem with my air bag light going off ever since it was driven off lot. Dealership fixed and I did not have a problem ever since. In June 2003 I had floor wiring harness replaced. The end of oct, beginning of sept I needed my alarm system switched out with new key system (the alarm system is something I needed to have done). Since the alarm system was changed out, my air bag light has been going off since and they tell me there is a sensor problem again but I would have to pay for them to fix. This is the same problem I had when I drove the car off the lot. Now that the warranty is up they do not want to fix. They want me to pay for a problem that I feel is theirs. Its only been 3 years that I have had this car and I fill that this is a safety issue. Why would I keep having a problem with my airbag indicator? this airbag can go off anytime or may not go off when it is really needed.

Air bag service indicator stays on.

Air bag system replacement. Ph.