If you are thinking about booking a flight with united airlines, and accidentally book it for the wrong day, and then buy a ticket with southwest for the right day, and then try to use your unused ticket with united to purchase another ticket for another trip about 6 months later, DON’T. Unless you have an extra $600 to throw around. Geez.
What the heck happened???
And who doesn’t have an extra 600 lying around?