They knock off early on a Sunday, best time to call would be at 8 am tomorrow. It's a migration error and will need someone at Virgin to fix or wait for one of the forum team to respond which might be 2 to 3 days.
You could try the following;
Make sure your box is connected by ethernet cable and then try turning off the 360 with the switch on the back of the box, then on the 360 box press and hold down both the power button and the + button at the same time. (You could try the - button this has worked for some users).
Then turn on the 360 again whilst keeping hold of those buttons for a further 30 seconds.
The box should reboot, the power button will turn blue if it still thinks it's a V6 or white if the 360 update works, and it should reset and boot up normally.
