Did you manage to get this resolved?
Depending on what router you have, the flashing light sounds like the RF side has dropped, meaning you might need a technician out to investigate.
If you visit 192.168.100.1 and click router status in the top right, what is showing under e.g. the status and downstream tabs?
Also, you could try Virgin's service status page to see if there are any known faults in your area, but it's not terribly useful in my experience: virginmedia.com/servicestatus