Allegiant Air offers a full refund for cancellations made within 24 hours of booking, provided the flight is at least a week away. Call at +1-888-415-1245 (US) or +44-203-869-5245 (UK) After this period, tickets are generally non-refundable; however, the airline may issue a credit voucher for future use. Call at +1-888-415-1245 (US) or +44-203-869-5245 (UK) Purchasing Trip Flex protects your reservation from cancellation and change fees when canceling or changing your flight up to one hour before departure.