Hi
I am afraid we have a miscommunication.
I thought you were talking about the upper bolts in between the headrests. Where the belt slides down in the retractors.
That wrench is 12mm. And try not to use an open end but always - when possible - a close end and the best is 6 sides instead of 12 sides.
Make a picture so we know were you are working.


One ant does not know anything, 2000 are a super-intelligent brain. That's like this helpful forum.