I'm sorry to hear about your brother's mental health struggles, but I'm glad he's getting some care for the time being. I don't live in Melbourne so I don't know if I can help with that, but I imagine the hospital themselves should have some information about other options in the area. Otherwise, a good GP may also be able to provide some local suggestions.
Sadly, it can be hard to quickly and easily find a treatment and a doctor that suits us, and I know it can be really disheartening, but I hope it won't take you and your brother too much time or effort to do so. BeyondBlue's own support line can also be a good source of both support and generally information about what help is out there, in case neither of you have given them a call either.