Thermostatic/non thermostatic showers are usually simple showers and one you have to mix the temperature via the taps on off valve and the other you mix the temperature via the thermostatic cartridge lever. Most common fault is the thermostatic cartridge failing or the washers/cartridge failing so it is constantly dripping. We can repair all problems. Transgas Services 22 Akerman Road Surbiton KT6 5NS United Kingdom https://local.google.com/place?id=14846834777035625783&use=posts&lpsid=CIHM0ogKEICAgIDuxZHn9gE