If you have a "Promotion Code", this is how to use it.

After adding the products you want to purchase to your basket:

On the "Your Basket" page type the promotion code into the "Promotion Code" text entry field
Click the "Apply Code" button
After the above two steps the page will reload and any discounts will be listed against all applicable products and under the subtotal
Note: It is the customers responsibility to confirm the discounts they are expecting from the "Promotion Code" are applied to all expected products BEFORE they click the "Checkout" button. Promotional codes cannot be applied after an order has been placed.

Promotion Code Terms and Conditions
Only one promotional code can be applied per order (promotion codes cannot be used on the same order as any other promotion code).
Promotion codes can be withdrawn at any time.