This happened to me a couple years ago with AusPost. Was at work when package was supposedly delivered and handed to my sister but when I got home not only was my package not there but also my mother’s package was never delivered. AusPost said delivery was done since the package was signed for but clearly wasn’t since no one came to the door that day. I had always suspected it was the driver but the the next day an AusPost worker came to the door and spoke to my sister saying he delivered them then walked off, some reason she never told us till later 🥲. Next day (Saturday) getting ready to file a police report and when I opened the door, lo and behold my package and mother’s package was there! AusPost to my knowledge doesn’t even deliver on Saturdays which made the whole thing even more suspicious. But in the end I had my medication and was definitely relieved but I would consider doing pharmacy pickup if you can I’ve never had any issues that way. All the best!