if its an electri shower it wont be running though the combi boiler, it will have just a cold feed to it, if the shower is running cold its more than likely the thermostat has gone or maybe even the heat element, to be honest electric showers are repairable but can be abit of a pain getting the right parts on older models. if its new you might have a chance but more often than not it might mean replacing the unit
pid, February 2009
