Can anyone help please.

The hot water on our central heating system is not working and I have
tracked the problem back to the micro-switch in the Honeywell valve(it
was corroded and basically fell apart!). I can find plenty of places
to replace the whole head but I would prefer to replace just the
switch. It has a reference number on it of - V94234GJX54. Does
anybody know where I can buy one - preferably mail order or around the
London area?

Thanks in anticipation