Your best bet is to book a United flight that is just slightly over the amount of your Travel Bank flights, then wait more than 24 hours, then cancel the flight to receive future flight credit. Future flight credits can be used on United and non-United flights and also used for things like seat upgrades. FAQ is here: https://www.united.com/en/us/fly/travel/credit.html Biggest downside is that they expire 12 months from when the original flight was booked.