I use Aussie Broadband for on HFC, and their customer service team is beyond amazing and worth their price a few times over. I could not recommend another ISP in Australia as much as I would recommend Aussie.
Not only is the service team based in Australia, but they're knowledgeable and persistent. When I have an issue, they will call me back to check that everything is working correctly and you really feel the person you are talking to is invested in helping you. I'm able to talk to them about things like cgnat etc and they're all familiar with the technical aspects of their service to do what I need. I know if I were to call many of the other large ISPs, I wouldn't get much further than them telling me to turn my modem off and on again.
In fact (and in contrast), last year I had to deal with another famous Australian ISP because my roaming plan stopped working in London. After being escalated, I got someone from overseas on the phone who talked down to me, accused me of lying about my phone's configuration and claiming to be THE EXPERT OF ROAMING (despite being patently wrong about how ITU codes work). It was resolved two weeks later when said nameless ISP found the bug and fixed it for however many users.