If you're definitely missing channels that you're paying for, then you're best off calling into CS where they can probably resolve it there and then, or detail what you're missing and wait a few days for a forum member to respond.
For the second time this week I am missing 10 HD channels. The first time it happened I was on the phone to Virgin for an hour. Eventually it was escalated and the channels reappeared. Now, two days later they have disappeared again! I cannot face phoning Virgin again!! I am hoping someone on this forum can advise.