I am currently holding an international ticket booked at united.com, and I am within the 24-hour cancellation window.

The fare I booked is a K class fare, is non-refundable but can be used for another ticket with a $300 penalty.

I have now noticed that for $4 additional there is a "flexible" fare. It doesn't appear very flexible, but it provides for a refund with a $300 penalty rather than a credit with a $300 deduction.

The "flexible" fare that I want is, like the fare I booked, a K fare.

There are no more K seats available, so I can't rebook and cancel (and I don't want to risk cancelling in the hopes the K seat will go back into inventory.)

Can I get the telephone reservation people to refare the ticket at the "flexible" fare within the 24-hour period?

If the answer is yes, does the 24-hours start ticking again from the time of the issuance of the ticket at the new fare basis, do I keep the 24-hour period I already had, or does the ticket become non-refundable when the fare basis is changed.

And one more question - if the change is possible, can it be done by Twitter, or do I have to call?