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There shouldn't be any problems moving you to a flight where there is no award availability left. The wife and I are booked on an MFU itinerary (WT+ to CW) and our flight was cancelled, we were automatically moved to an earlier flight which had no availability and were upgraded
^
from a 777 to upper deck 747 
Originally Posted by starlight
I don't want to buy a Hummer!
Good god, who would?