Dhillier, the fix for the roof handle is very easy! I was very wary about fixing mine, but I followed Dave Allinson’s posts and the photos from ZXRichie and others in this thread and it worked perfectly. Total cost was about £4. Apart from Torx screwdrivers no special tools required.
Just read the thread from the first post on page 1 through to page3 to get the issues and method clear in your head.
Sorry can’t help with the window and seat problems, but my seat too works intermittently, so I’d be interested in any fix.
Good luck, but the handle fix is really very easy thanks to the guys who have posted their methods.
Cheers
Paul