I was with Virgin Media ADSL for several years, after jumping ship from the appalling Lineone/Tiscali. They had a shaky start, with definite ups and downs in service, then they levelled out as a bloated over-subscribed, over-hyped broaband provider that fell far short of their promised levels.
I stayed because I couldn't find another ISP cheaper that wasn't as bad or worse.
I've now switched to O2 who have so far been excellent.
2 days after leaving Virgin I was sent a bill for the next month's service. It took a 15 minute call to customer services who passed me around 4 different departments, keeping me on hold for most of the time. Turns out my account was still active, despite 2 weeks of them sending me letters and emails telling me they were sorry to see me go and confirming I'd been successfully migrated to another provider.
The icing on the cake was being told by the movers team (the final destination on my phone redirection trail) that if I still got charged for this current bill and I wanted a refund I'd have to phone up customer services again.
I will be so glad when I have left all trace of these incompetents far behind.