Leak from another property

[Ollivander84]

I'm being deliberately vague!
So say you live in an apartment block. Plumber has confirmed the leak is from the upstairs apartment, but to fix it requires the boxing (MDF type) taking off around the bathroom upstairs
They refuse. So the leak can't be fixed. What are the rights of the downstairs flat as their flat is being damaged by the leak?
For ease, assume management company are as much use as a chocolate teapot

Update - it's gone to housing standards at environmental health as no contact yet. And still leaking

You have the patience of a saint. Your neighbour and the management company are behaving appallingly. Fingers crossed EH can step in.

EH have definitely stepped in, both feet first
I'm not sure about patience of a saint... I'm raging. Plus I have to pay the excess to have the bathroom redecorated and make a separate insurance claim so even more time

Hopefully the final update
The pipes have been replaced, it was a severe leak and took 9hrs to get the pipes out and new ones in
The boxing in is being done Monday and then I am paying to have the bathroom painted