Modena 80e not generating hot water?

I have recently had a new bathroom fitted and at the same time was decorating and had removed 2 radiators in the living room.
Since completion I can only get hot water intermittently from the bath, shower and sink tap.
The plumber is saying that it is probably a problem with the boiler - perhaps air in the boiler and is suggesting that the removal of the radiators could be having some bearing.
The rads are back on the wall, all have been bled and the system re-pressurised. I can't see anything in the manual for the boiler about bleeding it.
Can anyone tell me what the problem is likely to be and should I press the plumber who installed the bathroom to fix the problem on the basis that it all worked ok in the old bathroom??