The seller or holder of a retail installment contract must give the buyer a written receipt for any payment made in cash. Upon the buyer’s written request, the holder of a retail installment contract shall give or forward to the buyer a written statement of the amounts of payments and the total amount unpaid under the contract covering transactions during a period not to exceed 18 months from the date of the buyer’s written request. A buyer is entitled to such a statement once every 6 months without charge. The holder may require payment of a charge not exceeding $10 for each additional statement furnished.