Hi there

I have a fairly modern combi boiler. It is located in a cupboard upstairs in a two storey house. Last year I had problems with losing heat in my radiators and each time I bled them I had to pump water back into the system (by opening valves on the base of the boiler). However, the radiators still need to be bled quite frequently but more worryingly now, the combi boiler pressure keeps dropping. I have to top up the water pressure at least every few days. Does this mean there is a leak in the system somewhere or perhaps that air is getting in somehow? Is this something that I can fix myself or do I need to get a plumber in?