I have an Ocean Alpha 240E combi boiler it's about 6/7 yrs old. There seems to be a problem with both the hot water and heating circuit. When the hot water is on it only lasts a short while, then the pump and flame cut out, after a short time both kick in again. The same happens with the heating circuit. This results in lukewarm radiators and very dangerous showers. I've tried cleaning both hot water and heating return filters, but as we are in a soft water area both were spotless. Tried varying the water pressure by closing the mains stop cock slightly but seemed to only work short term. Can anyone help please?