Then the fun began

On trying to pull the seats up, the centre seatbelt had locked tight (a bit like when you jam the anchors on, and the seatbelts stop letting out more belt).
Problem was the seat back was down, and the locked seatbelt meant it would only pull up by about 30 degrees, so i could not return the seat to its upright and locked position. To solve this I had to unbolt the seat back and unbolt the bottom belt mount, free up the belt and tie a knot in it to allow me to put everything back in.
Problems been sorted out now, but has anyone encountered this before?
Any tips to sort this, rather than getting the spanners out?