I forgot to use my promo code, can I apply it once I finalise my order? May 17, 2022 06:08 Updated Unfortunately once you have completed your order and the payment has been processed , you can not go back and add a promo code. See here for more information. Related articles My Promo Code isn't working, what do I do? Can I use my promo code more than once? How does the rewards program work? How and when do I apply my promo code? Can I use my promo code on all products?