Balcony responsibility

We have recently purchased at the auction an apartment with a balcony in a 4 unit apartment building in Victoria. We stupidly followed the advice of our mortgage broker and didn’t get the property assessed before purchase. After we moved in, a retired builder family friend drew our attention to the balcony being in a poor condition. We had a building inspector do an assessment and he indeed confirmed that it’s a safety hazard, that it’s dropping due to rotting timber poles that are supporting it. We don’t know the exact cause, it can be poor maintenance, weather or maybe something happened in the past that we are not aware of. The other owners say that it’s normal wear and tear and that insurance will not cover it, that we have to do it ourselves. I have contacted the insurance, but still haven’t received their response.
Also, the supporting wooden poles are placed on the neighbour’s lot under us. That neighbour’s lot is on the ground floor and the poles are in their courtyard. Our balcony provides the roof for their verandah, and they have table under our balcony. We have warned them not to spend time there.

My question is, since the poles are on that lot, do we have the entire responsibility for the repairs and maintenance, or is that a shared responsibility? Who can we contact in Victoria to ascertain that? Any information would help.