The switchpack is fitted to the plinth, so that has to come off first. Sorry I don't have photos as it's much easier to explain with pictures.
It's held on by two self tappers at the rear, and a nut at the front. You can see the self tappers, one at the top one at the bottom. The top one is a pain because the backrest gets in the way. However you can do it by pushing the foam out of the way.
The nut at the front is harder to see, you need to look underneath the seat. If you take the screws at the back out first, it usually ends up finger tight. When reassembling, only thighten it after the rear screws are fitted or you won't get them back in.
Once the plinth is off, disconnect the white connector to the switchpack.
Then, you have to remove a second plastic part inside the plinth. This is held on by a number of little plastic wedges. I've seen three on some, four on others. They just slide out, but don't lose them!
Once this is out of the way, the switchpack is just clipped in. You need to pull the caps off first, then use a screwdriver to ease the pack out.
To repair it involves dissasembly of the switchpack itself. I drilled and tapped holes where the pegs had snapped off, and then screwed and glued some screws into place. I had to grind the heads slightly once fitted, but both my cars have this fix done with no problems.
You may choose to replace the pack rather than repair. If so, please don't bin the old one as I could repair it or use bits to help another.
Incidentally, if anyone else has a broken passenger seat switch they could send me I could use that for spares too.