If your order has not left the warehouse and you want to make a size change, or for a model of lesser amount, we can make the relevant change and you get home the product you want. If you want to exchange for a higher priced product, we will cancel the order with the corresponding refund, and you will have to make a new purchase. If, on the other hand, your order has already been prepared, you will have to wait to receive it. As soon as you have it at home, you can request an exchange or refund here for free.