just had same thing wrong with mine - man came and changed teh thermostat / heater on the back now works fine - only took him 2 misnto fix it charged me £60 ( I thought that was a bit dear but it working now )
if u get part yourself d it looks very easy to change
unplug unit - remove the metal plate on rear by unscrewing the cover plate and then unconnect the connectors (in the hole bottom left) and unscrew heater thenjust replace in reverse order!
jane, January 2005