My auto-dim rear view mirror has gone opaque, with a large brown bubble at the bottom.  I've scoured the internet looking for a company that can repair them, but so far no dice.

I've toyed with the idea of a second hand one, but none seem to be available.  There are plenty of mirrors from the Mk2 8P, but the attachment foot looks different.  I'm sure the wiring would work.  It is not an MoT fail, but I'd like to keep what was an expensive option.

Any advice?

Unfortunately the only real cure is to replace it with a brand new item. They are very rare but various cars from this era suffered from.this issue such as the BMW e39. 

Cheers

Steve