I got fed up with Virgin Media - their website gave a 0345 tel number for help, but after numerous options it took me back to the same website/page!
I also thought about buying an alternative cheap mobile and to keep the same telephone number. I tried to get Virgin Media to send me a PAC code - but they demand you enter "PAC and date of birth!" (usually you just enter "PAC" and send the message) When I did this and sent the message, the response was "Sorry, our bad. We're having a few technical problems and can't do that for you right now. Please try again later when we should be backup and running". Pathetic.
I've now bought an IMO Dash from Tesco, a great mobile, for £4.99 and paid £10 for a no-contract pay-as-you-go voucher. So cheap and the phone is really good!