Call VM on 150 from a VM phone or 0345 454 1111 and report the fault, they are responsible for replacing any faulty kit. They should post a replacement out to you.
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.