Condensing Boiler Losing Pressure over night?

I have an Ideal Condensing Boiler (which is anything but ideal! and should be avoided like the plague)

Latest problem, It's losing 1 Bar of Pressure over night. I have checked every radiator in the house and there doesnt appear to be any leaks. Occassionally the boiler is dripping water underneath the boiler. (this time there is no water under the boiler but there is still a loss of pressure).

Every morning I get up, check the pressure and bring it up to 2 to cope with the loss of 1 bar pressure. But it's worrying because I dont want them to have to take all my floorboards up etc (although I would have throught Id have had water through my ceiling if it would have leaked under the floor boards).

Last time, the AA came out, noticed a few worn out rubber washers, changed them and thought that had fixed the problem, but it hasnt.

Any Ideas?

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plumber chiswick
central heating chiswick