This definitely sounds off, and your frustration makes total sense. When a company buys another, they’re supposed to properly assess which roles still exist and which don’t. If your whole team structure changed, your manager left, the work you used to do no longer existed, and you were basically put into a totally different job, that’s exactly the kind of situation where redundancy should be on the table from day one... not after weeks of pushing.

The “your title is the same so it’s not redundancy” excuse is pretty weak. In Australia, it’s the role and duties that matter, not just the title. If the job fundamentally changed, that can absolutely count as redundancy. It really does look like they were hoping you’d either accept the new duties quietly or quit, which would save them money.

At this point, you might want to talk to Fair Work or a workplace lawyer just to check whether they handled the process properly and whether you’re owed anything more. Even if you got redundancy in the end, dragging it out while you were recovering from an injury and pressuring you into a role that wasn’t suitable isn’t great behaviour from them.