passenger air bag turns off with passenger in seat

When my passenger puts on her seat belt, the warning light comes on indicating the passenger airbag is turned off. I had the car back to the Parks Ford dealership where I bought it 3 separate times and was told (1) they couldn't find a problem; (2) we were doing something wrong (e.g.: she wasn't sitting back in the seat, which was wrong); (3) the car thought she was a child seat (which isn't supposed to be in the front seat anyway). After they were finally able to duplicate and confirm that the passenger air bag turned OFF when a small passenger was in the seat, they told me my wife was too small/light (she weighs 130). The service manager turned a shade paler when I pointed out that meant a child could not be safely transported in the front seat of the car. He simply said they "could not" fix it because it was a "factory setting". I then took the car to a different dealership (Santa Fe Ford in Alachua Florida). The service rep listened to my description of the problem and immediately said it sounded like a sensor needed calibration. In one day they fixed the problem about 85%. It is now POSSIBLE to get the passenger air bag to not turn off, but it requires that my wife actually slide her weight forward in the seat and push down.