Kaizer Motors is your man, Medway in Kent, I cross the bridge from Essex for my service from him and I cannot be more happier. Sure others travel further for some Kaizer love!
http://kaizermotor.co.uk/
You're right, I had the same issue and replaced the slave cylinder when I first bought mine a few years ago, sadly didn't spot it when I bought it (second hand private), but that was run cold.