It is a shame you don't pay by direct debit. They have to inform you of what they are taking I think 14 days before taking it, as part of the Direct Debit agreement. Since VM email that info to you, and since they had taken your internet down, they couldn't provide you notice unless they sent you a letter through the post. If they then took the money without giving you advance notice you could claim it back from your bank and get VM a firm knuckle rapping in the process.
You have to plan ahead for these things...

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