Does it explicitly say that the $275 is a change fee, or could it just be a difference in the underlying fare between the two dates? There is a line in the original T&Cs that seems (in my layman's eyes) to cover that:
Fare rules for your ticket
CHARGES FOR CHANGES AND CANCELLATIONS
• NOTE - NO PENALTIES UNLESS OTHERWSIE SPECIFIED. REFUND WITHOUT PENALTY PERMIITED AT ANY TIME UNLIMITED CHANGES WITHOUT PENALTY PERMITTED AT ANY TIME -------------------------------------------------- A CHANGE IS A DATE/ OR FLIGHT OR ROUTING CHANGE IN THE EVENT OF REROUTING THE FARE MUST BE RECALCULATED FROM POINT OF ORIGIN -------------------------------------------------- WHERE THIS FARE IS COMBINED WITH ANOTHER FARE THE PENALTY CONDITIONS OF THE CHANGED FARE COMPONENT WILL APPLY. WHEN MORE THAN ONE FARE COMPONENT IS CHANGED THE HIGHEST PENALTY OF ANY CHANGED FARE COMPONENTS WILL APPLY // CHANGES BEFORE OUTBOUND DEPARTURE // WHEN THE FIRST FARE COMPONENT IS CHANGED THE ITINERARY MUST BE RE-PRICED USING FARES IN EFFECT ON THE DATE THE TICKET IS REISSUED -------------------------------------------------- WHEN THERE ARE NO CHANGES TO THE FIRST FARE COMPONENT BUT OTHER FARE COMPONENTS ARE CHANGED. THE ITINERARY MUST BE REPRICED USING FARES IN IN EFFECT ON THE PREVIOUS TICKETING DATE OR ON THE DAY OF REISSUE - WHICHEVER IS LOW -------------------------------------------------- // CHANGES AFTER DEPARTURE // THE ITINERARY MUST BE REPRICED USING FARES FARES IN EFFECT ON THE PREVIOUS TICKETING DATE. -------------------------------------------------- UNLESS OTHERWISE SPECIFIED -------------------------------------------------- WHEN THE NEW ITINERARY RESULTS IN A HIGHER FARE THE DIFFERENCE WILL BE COLLECTED -------------------------------------------------- WHEN THE NEW ITINERAY RESULTS IN A LOWER FARE A REFUND OF THE RESIDUAL AMOUNT WILL BE MADE --------------------------------------------------
My
bolding - a ticket will be re-priced when you make changes, based on the underlying fare rules. As it's an MFU, it's quite possible that there is a difference in the underlying fare between the original date and the new date, although only you will know what those are.
My
italicising - This section indicates that the highest penalty is charged, so depending on the fare buckets and conditions for the non-MFU leg, then this also may be the reason for the change fee (or, in fact, new fare).
I think this highlights the difference between a pure awards ticket and an MFU, especially where there are component of a ticket that haven't been MFU'd. I know it sticks in your throat, but another way to look at it is how much the ticket would have been in the upgraded cabin should you have had to pay cash for it in the first place? I'm sure the difference would have been much more than $275...