Rather than returning the gown that you bought due to the improper rate of interest quoted you versus what you are supposed to receive, you should keep the dress and insist that you are to receive the 0% interest on your purchase for the 12 months.After all, you have a written letter from the seller stating there was an error on the interest rate given you. Under the law, you cannot return the dress for a full refund. However, you should receive the 0% interest rate.