It depends which hub you have. On some a flashing wireless light can be normal, depending on the colour of the light. There is a VM help page HERE that gives more info about the lights on the various hubs.
If you can give us a bit more information and describe the problems you have been having we might be able to help.
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.