Also if you gate check a bag they usually don't charge you especially if its done last minute on any airline. Also did you try to get them to just waive the third bag fee rather than just going back to your original F class flight? There are a variety of ways the bag tag can be coded in the computer so as to not generate a fee. Such as tagged as a baby stroller, disability assistance device, possibly under millitary, etc. Also the agents have a way to just waive an ordinary bag fee. If you are checking a bag with a non airline contract employee, they have fewer priviliges in the computer system. Although one time on another airline my record had been documented to allow 3 free checked bags, but the contract skycap had trouble waiving the fee. So he tagged one bag as a stroller which runs as $0. So he found a way to work around the problem. Also maybe if you give them a tip they would find a way to waive the fee for you. haha