Dd had a new phone on contract around 18 months ago. She then discovered boys (well, one in particular!) and her bills went through the ceiling.
When the contract expired, I phoned to confirm we wouldn't be renewing, but a very helpful chap at The Carphone Warehouse told me that he could offer me a fantastic package, the clincher for which was that if she went £10 over her limit, she wouldn't be able to make any further calls.
I've just had a bill for £105 - phoned them - and they have basically said, we might have said it, but we didn't mean it, and we can't guarantee it - so tough!
Am I mad!!! I shan't let it drop (obviously), but in the meantime, beware - don't trust the lying little toads!