To whomever this may interest, similar network limitation experienced here, but without Virgin Mobile advising of this until after the contract was signed.
First, I was told my Samsung handsets (brought over from Optus) are not compatible for video calling. Then Technical Support instructs to perform a factory reset.
This week, finally, the truth comes out from Customer Relations who advises that this is a KNOWN NETWORK ISSUE ever since Virgin Mobile transitioned to the Optus 'Yes'.
Incredibly, I was also advised that this issue presently exists with new generation Galaxy models, but if you have a Galaxy S4 or prior, video calling works. This advice is false and misleading, since video calling is available on newer generation Samsung mobiles that can use new VoLTE technology.
The issue here is that, despite Virgin Mobile marketing and selling video calling and video call-capable handsets, it is their network that does NOT support this plan feature and they are removing it from the ROM of their new handsets. For the record, video calling on my handsets WORKED without a problem on the Optus network proper.
May I encourage people in a similar position to complaint to the TIO (Telecommunications Industry Ombudsman), but also to the ACCC (Australian Competitition and Consumer Commission). The ACCC will take action if enough customers complain, because this is a blatant breach of consumer guarantees under the Australian Consumer Law (ACL). Virgin Mobile should not be marketing and misleading consumers about the availability of video calling, and then when it's discovered that this feature is not available, blame Samsung.
That Virgin Mobile's Customer Resolution Department (CRD) is incapable of understanding the broader consumer issues and ACL contravention further adds to the damage and insult. Aside from lame resolutions (e.g. small refunds) they will also suggest we use app-based video calling such as Skype. Why? So you can make more money on the extra mobile data usage? UTTERLY DISGRACEFUL.