VIC - Sagging Ceiling due to faulty balcony

Hi All,

I've got a sagging ceiling that was recently patched up as a result of a balcony repair. Balcony has fixed the water leaking issues to other areas but it looks like water is now leaking through some cracks in the ceiling.

Here are some pictures:
https://imgur.com/a/sKvXzqj

Does anyone know of a repair who could:

1. Rip parts of the plasterboard down to check where the leak is originating from
2. Repair the sagging ceiling once source of leak has been identified

Insurance have asked for 3 quotes, so does any one know who can undertake the work above? Location is Melbourne.

Thanks!