How can I fix my Triton LP Shower?

My Triton LP shower gives very hot water even at the lowest temperature setting on the thermostat. Some time ago the temperature adjustment knob developed a problem whereby it could be turned right round, though this has now stopped. I am wondering if I can fix the temperature problem by removing the knob and re-aligniing it (presumably its spring loaded or something) or whether a whole new thermostat unit is needed.

The problem definitiely lies with the shower as the other shower we have runs fine. We derive our hot water from an immersion heater, which is working properly and is correctly set.

Thanks in anticipation.

Andy
September 2008