If not sorted yet then note that sometimes it can take 2 or more weeks for the accounts to be recognised.
If when attempting to sign in to your Virgin account however you get asked if you wish to link your Virgin/o2 accounts BUT it throws up an error as it constantly did for me, TRY doing it via your web browser on your mobile (no need to use or even have any Apps installed on mobile).
I use same laptop on home network with Chrome, this is identical to the Chrome browser on my mobile with all same settings, extensions, etc BUT on laptop it refused despite trying every fix imaginable. Then tried in Chrome browser on mobile & hallelujah linking worked first time, after that I was able to login as usual on laptop.
It's a sad fact that Virgin don't link the accounts automatically when a customer first joins Volt, or at least provide the option at that point so they can assist with any issue.