Putting the fittings in the dishwasher isn't really an option since
they are in use every day so a week is impossible. Besides some of
them are scratched or cracked. White moulded switches and sockets are
so cheap so I want to replace them.

I realised just after posting that a hacksaw or a Dremel is whats
needed. I haven't used my Dremel for ages so I'll have to check I've
got some cutting discs. Tim I was trying to get hold a square file. I
assume a full size file means its 8" long? I also can't find a coarse
one most of the ones I've found are second cut. Does it make much
difference? I found this:

http://www.mptools.co.uk/products.asp?partno=DR44956

Would this be suitable?

Cheers!