Dear Your letter informing us that the (missing item) for your new (product) was not included in the carton has been brought to my attention. There is a package on its way to you now that includes the item and a little something extra. This is our way of saying how sorry we are for having slipped up, and thanking you for choosing the (name of product). If I can be of assistance to you in any way in the future, please call us at any time.