I booked the wrong date. As soon as I realized, I corrected it. I booked for the 20th, but the terms and conditions said cancellation was only allowed before the 19th. That's terrible policy, because previously you could cancel just a few hours before departure. They suddenly changed the terms and conditions, and I lost money. I submitted a request for a review and repurchase, but it was unsuccessful. The purchase process clearly stated that cancellation was possible. The options for purchasing were also quite complicated, which was difficult for someone like me who isn't very good at English.