In message , Adrian
writes
If the door is "buzzing", that suggests that the unlock signal is getting
through. Are other flats having the same problem?

Either way, surely this is a building maintenance issue, as the door
entry system maintenance should be part of your freeholder's
responsibility.

It may be buzzing, but is it buzzing as loudly and strongly as before?
Could you be missing a common return and it's trying to loop back
through some other part of the circuit? Does anything abnormal happen
when you try to buzz people in, apart from it not working of course?

--
Bill