Hi,
I just checked the APIs documentation of Australia Post :
developers.auspost.com.au/apis/pac/refer...cel-domestic-service
developers.auspost.com.au/apis/pac/refer...nternational-service
They still reference the same things we relied on when developing the Australia Post v2 plugin years ago.
So, it should still work the same.
Also, if it "stopped working", the plugin is supposed to display an error message on the checkout explaining what the problem is.
You don't mention it. What error message did you get ? Did it create an error for all users, or only with a test you made with a specific shipping address ?
Access to the test website will probably be necessary. First, please make sure you're able to reproduce the issue there and provide the necessary instructions to do so. We're based in France. Please go through our contact form in order to provide the access:
www.hikashop.com/support/contact-us.html
Ideally, please make sure the backend access has access to the HikaShop configuration page, and if you can, please also provide FTP access as it might be needed for debugging.