1.2htp Engine high oil consumption

Hi there we have a Skoda Fabia 1.2 HTP engine code CHF, it is using a large amount of oil but not smoking much. We did a compression test and found that cylinder 3 is well down on the other 2. Would this be likely a piston ring or a head problem. Valve stem seals and valve guides? Would it be easier to get a new head, if so are they interchangeable between engine codes. Any advice would be much appreciated