If you have a coupon/promotion code and you wish to use it, you can do using by entering it into the Promotion Code field on the View Cart page during the service ordering process. If the coupon/promotion code isn't applicable for the ordered service or it doesn't meet the requirements for the code (for example: you've selected monthly billing for the service, and the code is for annual billing only), an error saying that the code doesn't apply to your items will appear. You can use the edit option on the service in the cart to change the details as needed and correct them.