Constant outages, breathtakingly incompetent billing department, and they may damage your credit score as well. Virgin Media sent me an unexplained bill for £9 several months after my service was switched to a competitor. I was on holiday when it arrived (in August), and I'd obviously stopped the direct debit as the account was closed. They issued a credit default notice to the credit agencies - even though I paid the unexplained bill as soon as I was back from holiday - and it's damaged my credit forever. They now admit that the bill was probably issued in error and that I'm due a refund for it, but the damage to my credit is done. And they say there is nothing they themselves can do to get the credit agenices to correct it.