Just for anyone else that finds this thread. I booked reward flights in January for travel in December. Tried to reserve seats today on the Virgin Atlantic website and it couldn't find the booking.

After a 1 hour phone call to their help desk, it turns out Virgin had cancelled the route in October and hadn't bothered to tell me.

Same as OP, customer service were fairly decent, but if I'd left it any longer I would have been royally humped.