The seat removed from the car
First thing was to undo the screw holding the plastic cover on behind the seat belt fastener
Onto the other side
Unclip the outer plastic cover, to reveal the screw
Pop off the back adjuster
and using a flat blade screw driver, remove the outer cover of the height adjuster to reveal two more screws
There is also another screw on the underside of the large plastic cover
All the plastic trim removed
Then, you can start to pull over the piping that is holding the seat to the frame
Also, on the rear of the seat, unclip the guide holding the rear of the seat cover on
Now, you can slide the base out from under the back of the seat. The front lifts up, and the rear will just pull out
Now for the bit that REALLY pissed me off. It wasn't the foam that was collapsing, it was the lining of the leather that had come away, and folded over on itself!
This is originally stitched in, and glued on. The glue had come away, and it had ripped away from the stitching. I also didn't have any fabric glue. So, after 10 minutes trying to think where I could get some from at 11pm on a Sunday night, I just decided to pull it all out.
I put the cover back on the foam, and the creases have gone, and the bolster is nice and smooth again.
Putting the seat back together is the exact reverse of taking it apart. The old foam was still is pretty good condition, but I've used the new one anyway, and will keep the old one as a spare in the loft.
The seat back together with the offending bit of cloth
The nice smooth bolster
and the bolster before