All my designs are created on Printify. Printify is a print on demand company, all products are unique and produced per order. Returns or exchanges are not supported if you ordered a wrong size, color, or simply don't like the product. Their Print Providers don’t have inventory space to keep the unwanted items.
"Once an order has been sent to production it is sent to the Print Provider and you can no longer edit any details or cancel it. If the shipment details were incorrect, or the customer ordered the wrong size or color, Printify is not responsible and will not offer replacements or refunds.
However, we can offer a replacement order free of charge or a sales credit, if there are any issues with the order, like manufacturing error, printing issues and such." (Printify)