F-saver on a 2-class domestic flight = C-saver on a 3-class domestic flight = 50K miles RT. If 50K miles is what you paid, you should have received a seat assignment in C on the 3-class 777. I don't know what your UA status is, but unless you're UGS you don't get to upgrade award tickets. One thing the agent could have done if you really wanted to fly in F: If XF was available, agent could have redeposited the 25K O/W miles price, and deducted 35K miles for the O/W saver mileage award. I think in this case, with the equipment swap, you could have made a case for all redeposit fees to be waived. But the bottom-line is, if you switched from a 2-class config a/c to a 3-class config a/c and still wanted to fly in F on the 3-class, you'd have to fork out some extra miles: 10K O/W for saver, 20K O/W for standard.