Can't upgrade codeshares
Called into MPC to process an upgrade for CX5809. Two different agents told me that codeshares can't be upgraded and that I had to book under KA809 and then the upgrade would work. Is that correct advice and/or a new policy?
So I changed the flight from CX5809 to KA809 and had to pay some minor tax difference during reissue.
Then, I could process the upgrade.
Has anyone encountered this issue before?