For purchases (1 item only) made using a coupon code, the discount will be segregated by item level. System will determine the percentage based on the value of the item. Refunded amount will be the final amount paid (minus delivery and membership fees).
If your order consist of more than one item and where the promotion or discount is applied to the entire order, the value of the discount will be divided among the items. If only part of the order is refunded, the refunded amount of each item will be less the discount applied, which is segregated by the system.