B-pillar is the one behind the front row seating (where the seat belts are attached), so if you are fine up front and have a gap in the rear just adjust the striker. There is a 19mm nut on the striker, loosen it, move the striker in towards the body, and tighten it down again.
If you mean the A-pillar in front of the front row seating then you will need to repair your hinges.