I wouldn't go so far to say as it doesn't happen, but in this case, my understanding of Vodafone's communication is that they will not bill the customers for these amounts at all.
In any case if any company is nefarious enough to devise such a strategy, they ought to at least be clever enough to add just a few quid here and there on some bills, which might be paid without question, rather than 4-figure bills that are certain to be questioned / refused.
Biting the hand that feeds IT
