New member could do with a bit of help. Keep reading about heater problems and this cock valve hose to matrix both getting hot but still only getting cold air in car. Heater control knob stiff and will not turn to all settings just springs back. Is this valve repairable or is it easy enough to get a new one. sorry to ask again about what seems to be a common problem but am relatively in experienced with seicentos but would like to get it working again