Open the Application for Refund; you may fill it out online, but then you must print the completed form. Sign the form in the presence of a Notary Public.Instructions: Please provide payment verification for your refund claim (e.g. Over Payment Refund Letter To Customers Template. Com once your account is validated. In this article, we'll show you how to write a refund request letter template that not only grabs attention but also persuades companies to act in your favor. To request a refund for overpayment, follow these steps. Complete the Overpayment Refund Request Form.