I have been with virgin.net for 2 years. Up until I upgraded from 2mbps to 3.5mbps
Problems only happened occasionally. The upgrade, in April gave me a very slow unstable connection. In the day, I get a speed of around 200 to 350kbps. I play a lot of online video games who measure your connection by the ping. The servers I play on have a ping upper limit of 150. I get around 250 to 300. I have a friend whose a Microsoft certified professional and has checked my pc. No problem my end but virgin say the problem must be. Technical supports keep blaming BT for nothing being done about it. Other than a line test..
After 7 months of going round in circles I have had to put in a complaint to www.ispa.org.uk but first I went to www.ofcom.org.uk to help them with the status report. Where they build a profile of how a company performs. If you join you may have a good connection for some time, but if things go bad your on your own.