To edit your subscription you will first need to login to your account »
If you checked out as a guest when setting up your subscription or cannot see the subscription in question in your account please get in contact with our support team who can help you with setting up an account linked with your subscription.
Once you are logged in to your account navigate to the subscriptions tab and locate the subscription you would like to edit.
Click the show products button to expand your subscription details
Click "+ Add another product to this subscription"
You will the be presented with 2 dropdown options, the first is to choose the product you would like to add the second will let you select the quantity of that product. Remember that this subscription will remain the same frequency as when first set up.
Once you have selected the product and the quantity, click "Add"
You can add multiple products at any time and once you have clicked to add them they will be saved to that subscription for any future run dates.