Sorry not a question rather a solve.I had no hot water from my electric shower.I was going to buy a new one as it is quite old anyway.When I opened it up for a quick look anyway I noticed something that didn't look quite right.It was a little switch just sort of hanging there.With further inspection I realised the switch should be operated by a cam on the cold/med/hot selector switch.There is another switch which is mechanically operated by the cam and the loose one fits on top of this one and is only held in by a small clip.Popped it back in and Bob's your uncle,hot water.