The error is being sent by the web servers, so the fault lies with the remote site not VM. They could be blocking your IP address for some reason and both the sites are run by the same company, the Arcadia Group.
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong If my answer solves your problem please mark it as helpful as it may help others My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.