[LeRich]

I assume the car is a saloon as the latch mechanism on saloon rear seats is rubbish. Within the seat back are metal bars that engage with the latch to lock the seat in place and are release when the shoulder buttons are pushed down.

The bars often misalign so won't engage with the latch, instead blocking the seat back from pushing all the way back into their upright position.

If you drop the seat back forward you will see the bars - give them a tweak to see if they move.