Ticket validity
If I buy a ticket, for how long is it valid (for rebooking/changes)? Is it 12 months from the purchase date or 12 months from the flight date? I'm asking because I would like to buy 2-for-1 upgradeable Flex tickets with my Virgin credit card for Jan 2015, but due to the recent credit card changes I will have to make a booking before 30 Nov 2013.