I'm still upset with them: A couple of years ago, Linux support for Rust (the game) was discontinued and the publisher said that all Linux users would get a refund on Steam, regardless of play time. I tried several times but all my attempts at getting a refund were rejected.
Not much you can do - if the machines decide you don't get a refund, well, then you don't. I haven't bought anything on Steam since.
Only if there's the possibility of a massive fine involved. The ACCC receive FAR too many reports to action any more than a tiny percentage of them. More often than not they respond saying they can't confirm or deny any violation, but you should try mediation.
The threat of the ACCC is usually enough for international companies to provide the refund, in my experience. Link them to the Repair, Replace, Refund page[0] and you're good.
Hard to tell. It's Steam that refuses the refund, no idea how the decision is made. Apparently others managed to eventually get the refund by trying again and again; maybe I gave up too soon.
Not much you can do - if the machines decide you don't get a refund, well, then you don't. I haven't bought anything on Steam since.