"Revolving charge account" means an arrangement between a seller and a buyer pursuant to which:
(1) the seller may permit the buyer to purchase goods or services on credit either from the seller or pursuant to a seller credit card;
(2) the unpaid balances of amounts financed arising from purchases and the credit service and other appropriate charges are debited to an account;
(3) a credit service charge if made is not precomputed but is computed on the outstanding unpaid balances of the buyer's account from time to time; and
(4) the buyer has the privilege of paying the balances in installments.