What worked for me at this point at least a couple of weeks ago - perhaps try this online.

Change the flight to a date in the future with the upgraded legs in economy - before confirming the change, it clearly listed the upgrade fee to be refunded to original payment - and I got an etc for the fare difference.

I took a screenshot and indeed, the upgrade fee was refunded to my credit card within a day.

It is something you can try online - and if you don't see the refund, don't follow thru.....