Another issue to consider. The seat belt tensioner was on the passenger side. "If" they knelt in your passenger seat to put the new tensioner in, they may have broken your passenger airbag occupancy sensor. Unfortunately I know from personal experience this one :-( And, like me, you have a 2007. BMW is replacing them through 2006 under an extended warranty, 2007 we are SOL. Same exact Takata part ....... I wonder who decides arbitrarily what year to cut off the free fix. You can turn off the sensor via the programming software (code not active), but if you don't have the software, again you're SOL .......... the dealer won't do it. These things are so fragile. There are members here who have replaced the sensor only to have the new one break a couple of years later. It's an expensive fix at the dealer. Seat has to be removed, leather removed from the bottom, new sensor put in the seat and the leather replaced.
