The only sure fire way to get a Hub 3.0 is to upgrade to a package that needs one e.g Vivid Gamer or the Homeworks 300Mbps tier. You might be able to get the retentions team to send you one for the cost of postage, but that isn't guaranteed. To get to that team call VM and take the "Thinking of leaving us" option.
If you want better wireless the best solution is often to get your own router and put the hub into modem mode. It is what I and many other customers do and it can make a huge difference.
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong If my answer solves your problem please mark it as helpful as it may help others My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.