Demon Internet

I was with Demon for ~3 years, no real problems, left seemingly without any issues. Signed up to O2 Broadband a few months later, and deleted my old direct debit details from my online banking. (they obviously weren't using it anymore, so why keep it, right?)

 I then received a threatening letter explaining I could be disconnected because I cancelled my direct debit...even though I hadn't paid Demon for months. I ignored it, thinking they were just being stupid. But no, they must've contacted BT as I now no longer have any internet connection! The line was literally unplugged, and O2 had nothing to do with it - they are now trying to get me connected again.

How dare Demon falsely use my details to disconnect me from my new ISP.

 (Aside: speed was ok during my subscription, price is now largely beatable, but obviously they don't know how to handle data properly, which is worrying.)