Owner Refusing Access to Common Property

Hi all,

I live in a 1940s apartment building. There are 2 hipped tiled roofs, one of which is accessible through a hatch in the stairwell. The other is only accessible through a hatch in the kitchen ceiling of the top-most apartment, which is currently unoccupied.

We have an NBN representative coming along to inspect and likely install a connection for 2 units and s/he needs to access the roof spaces of both roofs. Unfortunately this owner of the apartment with the access to our roof space is refusing access ! I would have thought that there is some Strata legislation that states that an owner can’t unreasonably refuse access to common property ? Especially as the apartment is currently unoccupied. Can anyone point me in the right direction ?

Thanks in advance for any advice you can provide,

Blanchie