Originally Posted by
corbomite
Aside from the bidding system does CX allow upgrading tickets to a higher class for a single segment or a single trip with cash? (e.g. I buy ICN-HKG-DXB-HKG-ICN in Y and only want to upgrade ICN-HKG-DXB to J later)
Also if this is allowed is this possible online or do I have to go through a local CX office?
it really depends on your sub fareclass.
If you bought a full fare Y or B, yes absolutely shouldn't be a problem. If you bought cheaper, the more discounted the more you'll run into problems because they can't refare a sector in many cases.
So I'm pretty sure the answer is "it depends". And no it's not possible online if it's allowed.