CX refused to amend a DONE5 at check-in
 

Arrived early at BKK for a DONE5 segment to HKG on CX. There was an earlier flight with D availability which I could easily make but the check-in agent refused to even look at changing it saying I had to contact BA (their desk was closed) if I wanted to change anything - I then had to wait for my original flight.

Was she correct or should I have pushed to see a supervisor - I had assumed that any Oneworld carrier can make changes on the day of flying?

Thanks

You have to go to a ticketing counter or call reservation desk. check-in agent can't handle it.
Theoretically, changing flight may require fare recalculation even same day flight change.

And, I strongly recommend not to ask touching XONEX reservation at check in counter.

In my past horrible story about BA agent, I asked an agent to change to an earlier flight at a check in counter. an agent casually accepted my request.
A few days later, I got to the counter at a destination for the next flight. An agent said I didn't have reservation,, because I did no-show on my previous flight.
You guess. The check in agent of the previous flight made a mistake when she changed my original flight to the earlier flight.

You are correct that any OneWorld carrier can make changes to an xONEx ticket (not only on the day of flying, but at any time). But being able to take over the ticket is different from being willing to. If you want to make changes to an xONEx, it's usually easiest to contact the issuing airline or TA in advance of the flight and have them do it. Sometimes an airline agent is willing to do it at an airport at check-in, but they have no obligation to.

Thanks for the feedback - something to bear in mind for the future.

One of the casualties of e-tickets is the ability to make this kind of change, which used to be routine and trivially easy with paper tickets -- they would pull the paper segment and sticker over the flight number and date. Now it is incredibly complicated to make the change, as it can cause a change in taxes and even recalculation of fare in some cases. Airlines dont care as this loss of flexibility doesn't affect their sales any.

I've had occasional success with moving to an earlier flight on a RTW ticket with some non ticketing carriers but in the 2 occasions with CX they would only do it if they took control of the ticket. In one case I had other changes that I wanted to make and the time to wait so I had them do it. It took about 90 minutes and ended up making the walk to my flight faster than I would have liked. In the other case I did not have the time to wait nor the inclination to reissue for just one earlier segment. I can also say that it has depended on the airport with a carrier (commonly yes with BA at Europe stations but hard, almost angry no at JNB). In several other cases in which I had a half a day's notice of what I wanted to do I got it done on the phone with either the EP or CK desk in time for the earlier flight.