What they'll do about your refusal to pay is to seek a judgement against you in the County Court and then send the bailiffs in to recover their money. Unless you want to end up with a damaged credit rating and the possibility of not being able to borrow money in the future (including getting a credit card) I would get in touch with your ISP a bit sharpish.
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.