Hi Nigel,
I recently fixed my rear calipers and discs on my Tipo 2.0 8V Aut. Took it apart, cleaned it (sand paper), replaced all seals and put it back together. The repair kit (£6) comes with the special "red brake lubricant" which you have to use for seals and piston. Only difficult part was putting back in the piston - it has to be screwed in while applying pressure at the same time. Used sanding paper to to clean the discs. Now everything works perfectly OK. While at it I also replaced the brake fluid - I had to remove trapped air anyway.
Michael