Air Bag On-off Switch problems of the 2011 Subaru Legacy

I have owned my Legacy since '14 and my brother owned it before that. He rarely had passengers ride with him and since I've owned it the few passengers I've had have always been heavier than me. (I usually did all the driving). About a year and a half ago, I took a road trip with a friend and he did most of the driving. We started noticing that when I was in the passenger seat the airbag light for the passenger side would say off. I tried adjusting my seat and changing positions and occasionally I could get it to turn back on. We switched seats and it immediately worked for him. I am 5' 9" and was about 150 # at the time. He is 5'8" and about 165. I took it in to the local dealership and they confirmed something was indeed wrong and told me that I must have spilled liquid on the seat that had ruined the sensors. This didn't make any sense to me because while I could not activate the sensors, the dealership employee being heavier than me activated it immediately when sitting in the seat. My brother and I are very particular with our vehicles and no such thing ever occurred. They told me it would cost a few thousand dollars to fix. I could not afford that expense and figured that I would just try to live with it. Fast forward to recently when I took another trip with a friend and this time I could not get the airbag to turn on no matter where or how I sat. I am now down to about 135 # and apparently the seat doesn't recognize that weight as an adult. I have been researching what to do for this problem because, as a fire fighter, I have seen what happens when an airbag does not deploy in a wreck. I have found many forums online with doz of people stating that they have the same problem and have been having it since the vehicle was new. This is an obvious manufacturing issue that hopefully has not cost any lives and soa needs to be held accountable for their dishonesty.