Front Seat Head Restraint problems of the 2009 BMW X5

My vehicle is BMW X5 30i 2009 model year. I suddenly had an error message on the dashboard screen saying "pass restraint system faulty". Dealer checked the problem and stated that this will not engage front passenger airbag and seatbelt restraint system if not fixed. Asked price was $1800 and paid $1500. Absurd price and should be covered by warranty -- its a safety system! I found out that there was an identical NHTSA recall on the same issue with other BMW vehicles just one or two years before this model year. The NHTSA recall code of that recall is 08v384000. I usually ride the car alone and have occasional passenger and never had any heavy load on the seat.

While driving on a freeway more than a week ago suddenly the airbag and restraint malfunction appeared for no valid reason. The next day my wife heard a loud metallic rub sound and park brake malfunction appeared. Searched online but no recall for this kind of problems for my X5 but it looks like its very common for Bmws. Need help!pls!thank you and more power!.