My SIL's F/F is displaying "freezer too warm" light. Fridge is too cold even on lowest setting & freezer not cold enough.It is also making a continual gurgling noise. I suspect the diverter valve is faulty which I believe means replacing & re-gassing, which I do not have the equipment to do. Can anyone confirm my suspicions & tell me if this is a common fault. Just trying to establish whether it's worth getting Hotpoint to do it or just buy a new F/F.