Hi there, both radiators in one of our kid's bedrooms can neither be turned off or reduce their heat when the central heating is on. As soon as the heating goes on the radiators blare out full whack and won't be controlled by the thermostat or their own temperature control (the spindle does turn on both). The rest of the radiators in the house do the decent thing and work at the desired temp as controlled by thermostat. Any help gratefully received