Hi Tom, I have been away this week so I can't help you locate which unit the noise was coming from.
That is the key, you have to find out the unit number where the noise is coming from and then report it to the building manager, who will then confront the residents/owners.
Additionally, If the noise is illegal, e.g. before 7am on a weekday, then you can go through EPA. Several residents, including myself, did this with unit #205 (see thread on this forum) with success. The EPA basically takes up the fight (with actual site visits and letters to the offending residents).
The noise makers in #205 have moved out recently. So with a little work, you can get success!
http://www.epa.vic.gov.au/your-environment/noise/residential-noise