have you tried bleeding the highest radiator yet?
and tell us about the drain-cock and hosepipe
Then I can tell you if you have that problem, and if you can address it yourself.
It sounds like a blocked feed pipe.
As a temporary solution you could put about 4 litres of water into the vent pipe and that should get it going over christmas.
Either use rubber tubing pushed round the bend or cut off the pipe on the vertical section ABOVE the water level in the cistern and then rejoin it with a compression coupler.
Tony
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