My experience is that people do not get them serviced but wait until something goes wrong until they get an electrician in. Yes an electrician is the person to contact. They are fairly reliable and the vast majority of problems (in my experience) are caused by people putting clothes on them to dry which blocks up the air vent - some people treat them the same as radiators which is unsafe. They have an in built safety device in the event that they overheat (due to clothes blocking the vent) but I am aware of a fire caused by drying clothes on an electric combination heater.