If you have a valid discount code this can be added at the checkout in the box provided, under 'Order Summary'.
On desktop: you can find the box on the right-hand side of the screen
On mobile: you may need to click the 'Order summary' dropdown to see the discount code box.
Please make sure you add your discount prior to checkout, as we cannot honour a discount after the fact.
If you are having further issues, please submit a help request.
*Note: only one discount can be applied at a time. For example, you can not use a Collector Club Reward and take advantage of a special offer discount at the same time.