(a) The seller or holder of a retail installment account shall promptly provide the buyer with a statement as of the end of each monthly period (which need not be a calendar month) setting forth the following:
(1) The balance due to the seller or holder from the buyer at the beginning of the monthly period;
(2) The dollar amount of each purchase by the buyer during the monthly period and (unless a sales slip or memorandum of each purchase has previously been furnished the buyer or is attached to the statement), the purchase or posting date, a brief description and the cash price of each purchase;
(3) The payments made by the buyer to the seller or holder and any other credits to the buyer during the monthly period;
(4) The amount of the service charge;
(5) The total balance in the account at the end of the monthly period;
(6) A legend to the effect that the buyer may at any time pay the total balance.
(b) The items need not be stated in the sequence or order set forth above; additional items may be included to explain the computations made in determining the amount to be paid by the buyer.