Coupon codes can only be used once per order. They can not be combined. If you have a credit on your account, this will automatically be applied to any order and you can still use a coupon code.
Coupon codes can not be used on already discounted mixed packs or flash sale items. If one of these items is in your cart, the coupon will register as invalid. Please ensure to reach the product details, as they will mention if coupon codes cannot be combined with a certain product/mixed pack. If you have any questions at all, feel free to contact us. We would be happy to help!