Simply replace the unfilled areas such as "" and "[date]" with your information.
Dear [supplier or supplier's rep],
Enclosed please find [name of item returning] which I am returning to you for a full refund. I am completely unsatisfied with this product, and do not wish to exchange it for another item.
This item does not meet my expectations, or the description of the item that I ordered. I am very disappointed in this order.
Please accept this item back, and please issue a refund of the total purchase price back to me. If you need to contact me to arrange for a refund, my telephone number is [phone number].
Thank you for your prompt attention to this matter.