Does the PM feel it’s necessary to reply to every complaint on the day it arrives? How about getting the PM to tell the tenant that any crises such as plumbing leaks will be dealt with asap, but other requests will be addressed as a batch, once a week. Maybe waiting for a reply will discourage the behaviour.
Could also be a mental health issue – lonely people will sometimes clamour for attention in dysfunctional ways.
I’d be asking about the reference checks that the former PM undertook.
You have my sympathy. Now that it’s so difficult to move a tenant on, those reference checks are no longer a quick tick-in-the-box that can be left to the PM’s junior assistant. They are as important as checking income and capacity to pay, if not more so.