remove handset and see if water flow improves
the going flow rate from an open ended hose is about 4 to 6 litres per minute when the shower is heating water at full power. Measure the flow rate by filling an empty pop bottle from the hose and timing how long it takes to fill it. If you have to turn the flow right down t, say to 2 litres per minute to get a reasonable showering temperature its possible that a section of the heating element has failed
garryk
March 2010