rear bench seat safety belt stuck won’t release to allow seat back to straighten up.
I expect the seat belt hardware is gonna have to be removed for an inspection. I had a similar problem on my prior VW Rabbit during a vacation drive, the seat belt wouldn’t allow me to move forward, it was locking me against the seat no matter what I did. I pulled over & removed the necessary stuff, along side a busy freeway is where this sort of thing always happens of course, and I saw there was a spring inside the seat belt hardware that had lost its proper springiness (tension) and that was causing the seat belt retraction mechanism to lock all the time. I had to slightly shorten the spring as a temporary fix until a proper replacement.
Any chance of removing the horizontal seat part so you can get to the retractor mechanism?