Air Bag Not Deploy problems of the 2009 Mercury Mariner

We purchased a vehicle from a family member that they had purchased from auto source in woods cross, utah (who specializes in rebuilding totalled vehicles). We recently took the vehicle in for work to be done on it, and the repair shop said that the seat belt tensioner had not been replaced in the vehicle, and the air bag system had been rigged to not trigger the airbag light to come on and that the module on it was bad, which may cause the airbags to possibly not deploy. They let me know that it is illegal for either of these things to be tampered with. I know that my brother-in-law did not tamper with either of these 2 items. It seems that this company is taking shortcuts with safety items that they have no business tampering with and then re-selling them to the public. I asked them to work with us to fix the issue and they are completely unwilling to even correct the issue. The vehicle airbag lights randomly go on and off (stationary and in motion) as we have not been able to replace the module yet. We had no idea the seatbelt tensioner was even missing.

The contact owns a 2009 Mercury Mariner. While the contact was driving approximately 25 mph, an opposing vehicle unexpectedly drove into her lane causing a head on crash. The contact suffered a pinch nerve in the neck area and body bruises from the seat belt. The air bags failed to deploy with the substantial impact. The vehicle sustained severe front end damage and was towed to an impound facility temporarily. The manufacturer was notified of the defect. The approximate failure mileage was 39,000. The VIN was unavailable.