Visual Voicemail Enabled But Not Working

I have recently switched over to a carrier (Vodafone Australia) that supports visual voicemail. I have enabled this in my carrier's settings and the voicemail tab still shows "Call Voicemail" without visual voicemail.

I have restarted my phone, deactivated and activated visual voicemail multiple times, reset my network settings, reset all settings and even erased my phone and restored from iCloud backup.

I am on the latest iOS update (13.6.1).

I went in store to my carrier to ask them why it wasn't working and they were unsure how to fix the issue as it was enabled on their end.

I tried erasing my phone and setting it up as a brand new phone without iCloud backup and visual voicemail was working perfectly.

How can I get visual voicemail working with my current iCloud backup?

I don't want to set up my phone as brand new without a backup because I will lose all my messages.