Next Door Leak Damaging Property

Access

The property next door to one that we are managing has a leak from its overflow that is causing damp inside our property.

I managed to organise our plumber to visit the next door property to assess the problem and even agreed to pay for the repair in order to sort it our quickly (especially as the neighbours consist of an old lady with dementia and a carer who is consistantly drunk).

The problem was identified by our plumber and when he revisited at the agreed time, no one answered the door. This was two months ago and we are still unable to gain access. As a result the damage to our property is becoming very serious.

How am I supposed to deal with this one?

Kind Regards,

RB