I have a domestic 2-direct-flight round trip booked for later this week. I have non-refundable (W & N) class flights. Due to illness, I might want to postpone this trip and re-book the same thing again for sometime in the next month.

Based on reading past posts--- I believe that if I call CO prior to departure and cancel, I will pay $100, and then have a credit for the price of the cancelled trip. Once I decide when I want to travel again, I can use this credit to book the new flights for myself. If the re-booked trip is less expensive than the original cancelled trip, I may get a credit / ETC for the difference. If the re-booked trip is more, I would have to pay the difference.

Is this correct? And if I decide to cancel, is the best way to handle it calling the reservations office, or can this all be done online? Thanks.