I booked a RTW in D. There was not D available when I wanted to go to GRU, so I was booked into Y. From what I have read here, FFCC means something like Full Fare Change of Class which means I paid for the class but there were no seats available. Should seats become available in the class for which I paid, I should get priority over others looking to move up. Or so I take from discussions here.

In the meantime, any thoughts on why C4 is showing for SFO but CO for ORD on the exact same flight from ORD???