I'm sure there used to be a bunch of cheap stores around the UNSW area but they might've all closed now.
I know a Taiwanese guy though who said he had a few decent conversations with him in Chinese, so maybe it was a language thing.
If you go in to MSY with the expectation that it's a warehouse that happens to sell things and that the staff are only there to 1) fetch things for you, and 2) handle the transaction then it is extremely efficient for both the business and yourself. No bullshit small talk, you can just go in, hand over a parts list, finish your sale, and leave within 5 minutes of being served when at a normal shop you might be there for 10 or 20 minutes.
It's a shame my local MSY closed down, they had hands-down some of the best shopping experience I've ever had.
ACCC won't help with individual cases, though they will follow up and levy fines like you've said. So you probably did the right thing for yourself by working around them in the short term. Apart from that you need a state authority, ombudsman, or something else for direct help.