Hi Sol
We decided to get a new boiler, as it was very old anyway. We still had a problem with the pressure rising when the new one was installed - it turned out that the filling loop valve was leaking, so the system was getting overfilled. I don't know if this is what caused all the problems, or whether something else had gone as well. I do know that the British Gas engineer was hopeless though, and after a dispute they refunded the charge.
HTH
Good luck
We decided to get a new boiler, as it was very old anyway. We still had a problem with the pressure rising when the new one was installed - it turned out that the filling loop valve was leaking, so the system was getting overfilled. I don't know if this is what caused all the problems, or whether something else had gone as well. I do know that the British Gas engineer was hopeless though, and after a dispute they refunded the charge.
HTH
Good luck