Let them come after you. Just cancel the service in the same way you signed up (send an e-mail if you've signed up online), and then stop paying them (or block the direct debits, or reverse the credit card charges). I haven't had any company that actually bothered to send it to collections (or even sue me). Only once I got a mail that I hadn't payed, and when I replied with the cancellation e-mail attached, they said "oh, ok" and never bothered me again.