The boosters are only free for Hub4 users, and even for free they're not worth the time and hassle
***** If you think my answer has helped - please provide me with a Kudos rating and mark as Helpful Answer!! I do not work for Virgin Media - all opinions expressed are of my own and all answers are provided from my own and past experiences. Office 365, Dynamics CRM and Cloud Computing Jedi
Sorry to hear that you're having issues ordering boosters from us, I have been able to access your account and can see that you haven't been able to get them ordered. Upon checking your account, I can see that unfortunately you don't qualify to get the boosters for free as @gary_dexter advised in his post.
If you wish to order boosters this will be at a charge of £3 per month onto your current subscription, would you like me to order the boosters for you?