You can access receipts of all of your payments, refunds and credit card charges online on the My Trip page. Access your booking by entering your “Last Name” and “Confirmation Code” and click “Search”.
On the next page scroll down to the payment section:
*For security reasons, attempted payments that have been declined and not successfully charged, will not be shown online.
If you have a myFRONTIER account, all purchases made while you were logged in will be detailed there as well.