They tell you that you can use the credit within 12 months. When you try to book the flight, there is no way to apply the credit yourself, so you have to speak with a rep to do it. They place you on hold for hours! When you finally do speak with someone who can help you, you are told there is a re-booking fee added to be able to use the credit, making it cost more than if you just purchase a new ticket without adding the "credit"! Bottom line is that they say there is no penalty and that you get the credit, but you do not. They are liars and unethical, at best.