I would never book an award flight on Air China again. I had a flight booked in April between VIE and BCN which every check showed was correctly ticketed and seats assigned. 24 hours before departure I attempted check-in and found the flight was no longer offered. Neither Lifemiles or Air China attempted any contact when the flight was cancelled. Neither Lifemiles or Air China could explain why, in the end I booked another award flight through Lifemiles and 2 days after the original flight departure time, I was able to get Lifemiles to cancel the award and refund all money and points.
It is extremely difficult dealing with Mainland China airlines in the best circumstances, and with an award booked with Lifemiles you have pretty much zero chance of support. Don't do it.