does the flow vary when you turn the dial up & down (temp dial), if it does not, then the heater tank is probably blocked, if the flow does vary, you should be able to find a new position where the temperature stabilises, try turning it to full cold, then turning it up a bit at a time, give it 10-15 seconds between adjustments, to allow it time to heat the water, for parts visit www.showerspares.com
GARY
May 2008