Hello,

I have something that looks like this:
http://www.toolstation.com/shop/Taps...r+Valve/p88398

A bar mixer shower valve. I don't know the make or age as it was in
the house when I moved in.

Lately to get hot water I have had to turn the temperature dial to its
maximum, 48 C, to get a hot shower.

I used to have it set around 38-40C but now that setting is lukewarm
at best.

Do these valves wear out? Can they be repaired? Or do I have to
replace the whole thing?

Thanks,
Stephen.