It is not possible to apply promo code to an order after the order has been completed. 

If you forgot to apply promo code, you may contact the organizer to cancel and refund your current order. Please note that cancellation policies vary per event.

If the organizer has agreed and refunded your order, please make another purchase using the promo code. To use the code, please click "Enter promo code" when selecting your tickets, enter your code, and confirm that the discount is reflected in the ticket price.