To (try to) avoid recourse to a reboot, you can also try following Home > Help & Settings > TV Care. There is then an option for "I'm missing some channels" that will send a refresh hit to your box.
Also make sure that, unless you've opted for the Sky Sports HD channels which attract a £7 supplement, that you're checking Sky Sports SD from 511 upwards (501 are HD). Sky Cinema is in HD as standard.
Otherwise, as per newapollo....
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks
Many apologies for our delayed response. Sorry to hear that your new channels weren't showing once you upgraded your TV package.
I'm hoping that the channels are now showing for you - as @newapollo advised, if you placed the order online, it can sometimes take a few days before the back office team process the order and activate the channels on your account.
If the channels are still failing to show, give me a shout and I can certainly look into that further for you.