Tickets purchased seven days (168 hours) or more prior to the scheduled departure date are eligible for free changes and cancellations within 24 hours of the date the flight was purchased. Frontier stores the ticket for 24 hours and then charges after 24 hours. This way your purchase will be sent to your credit card statement with a 24-hour delay. However, Frontier will hold the funds on your credit card.
Tickets purchased less than seven days (168 hours) before the scheduled departure date are not subject to free change or cancellation.
This may give you a little over 24 hours to change or cancel your ticket made directly through Frontier, only if you booked your flight seven or more days before the departure date. Tickets made through travel agents such as Expedia, Priceline, Orbits, etc., must pass in accordance with the 24-hour change and Frontier Airlines Cancellation Policy.