Recently my superhub has been turning itself on and off about every half an hour. This is obviously very frustrating when trying to play games. It seems to turn itself off then the white light starts to flash. After two green symbols show for about a minute and the it comes online again. It should be noticeable on Virgin's end that something isn't right and I would like to get it fixed as soon as possible.
I've had the same sort of issue for 3 weeks now; I have had about a dozen calls with Virgin which has amounted to 'you're a wireless user, and the more things connected to the modem and blah blah blah...' to 'we'll send an engineer out' only for them to cancel the next again day feinting that there was an issue in the network for my area. My modem is constantly rebooting and doing the lights you described, and when it is working, I am getting around 10mbps of the up-to 200 mbps I am paying for. So I feel your pain, honestly. But Virgin are still taking the full lot of my monthly payment even through for nearly a month they have failed to deliver even the national norm for broadband speeds (and that ain't fibre optics) so...
You could try phoning them and see how you get on. If you get somewhere better than me, let me know (-:
I rang virgin and they said there was a problem with my local grid or whatever you call It and technicians are working on it. The issue got fixed on the 3rd of Jan but it seemed to work the day before when they rebooted my router from their end. May be worth trying to get them to do the same with yours.