Except as provided in paragraph (2) of this subsection, any renewal, extension, or refund made under § 12-632 of this subtitle shall be by a written agreement signed by each party. If an extension is granted without any additional charge, the agreement need be signed only by the sales finance company. At the time a renewal, extension, or refund is made, the sales finance company shall deliver to the buyer an exact copy of the agreement. The agreement shall: State the name and post office address of each party; Identify the prior agreement to which it relates; Describe the goods; Describe any security interest or collateral security which was reserved or taken to secure the prior agreement and which is retained to secure the renewal, extension, or refund; and State the amount of the extended principal, the agreed rate of charge, the number of scheduled installments, and the time and amount of each installment.