We flew Sri Lankan Airlines recently and booked Economy seats. About a week before the holiday we got an email stating that we could place a bid to upgrade to Business Class. We placed a low bid and didn’t get the upgrade, however for the return flight, we increased our bid and did get upgraded. We paid about half what we would have done if we had booked Business Class in the first place.
Anyway, my question is - do other airlines do this auction thing?