Please help, I am now at my wits end, I have spent just over £500 on having my boiler 'fixed' over the past 3 weeks and it still doesn't work. The problem is the boiler keeps losing pressure, I have had the pump replaced, the pressure release valve replaced and the expansion vessel replaced and bleed all the rads to make sure there is no air in the system. The plumber has isolated one part from another to ascertain whether I have a leak but pressure remained constant indicating that this was not the case. The system works fine for a while but then needs refilling and reseting, I tried to do this this morning and I couldn't reset it - I am so fed up of having no hot water or heating and I am running out of money to keep having it repaired! I am also greatly concerned as to where the water is escaping as it isn't through the prv. Any advice greatly appreciated.