If the airline has issued reservation credits to your account, use them to book free flights during your next trips. Furthermore, you should know a few things about the airline's flight reservation credit. Spirit Airlines allows passengers to request reservation credit to book multiple flights until the credit is used fully The flight credit also is available to all guests associated with the original flight booking. The credit cannot be transferred to another person. Furthermore, no cash value is added to your reservation credits. Take help from the Customer Service Spirit Airlines via the following: +1 800 772 7117 or OTA: +1 888 894 2072.