Originally Posted by
craigthemif
I can't be definitive, but if you are changing from one off-peak date to another, the agent / computer system probably won't attempt to charge more Avios.
Just be aware that it's really hard to find award space in J and the travel dates for this promo are restricted. IB also aren't known for releasing more award space at the last minute.
You should book dates you think you can travel, and expect to cancel for a refund if you can't travel as booked.
Thanks. You're right, indeed. I was thinking that I won't find award space in J later on anyway, so if you want to change to Economy, who knows if they will refund the Avios difference.
As you said, the most likely scenario would be to cancel and get a refund.