Hi Weeal
I'm afraid that, once the diverter mechanism is knackered - which certainly sounds to be your problem, the only solution is a new mixer. They are not wildly expensive.(Under �20 from B & Q).
\You will need to turn off your water supply, and you really should know where to find it, in case of emergencies. Try tracing back your supply line from your kitchen sink - in fact, there is usually a riser with a stop **** under the sink.
If you have a stored hot water supply, and it sounds as though you have, there should be a gate valve beneath the cold water tank on a 22mm line to the hot water cylinder. Otherwise you will simply have to isolate the mains and drain down the hot water through the bath or water tap.
Changing the mixer should be quite straightforward. If you need help I'll be happy to talk you through the job on Yahoo Messenger (
[email protected])
Bosschester