(1) When there has been a transaction that results in a credit being due the customer, the following apply:

(a) If the amount due is five dollars or less, an adjustment must be shown on the next regular bill.

(b) If the amount due is more than five dollars, the customer may accept an adjustment to the account or request a refund. If the customer elects to have an adjustment made, it must show on the next regular billing. If the customer chooses to receive a refund, the company must issue a check within thirty days of the request.

(2) Overcharges. Once a company becomes aware that it has overcharged a customer, it must provide a refund or bill adjustment credit to the customer. The customer must be given a choice as to which option is preferred. The refund or credit must be the amount overcharged in the three years before the date of discovery.

(3) Prepayments. If a customer has paid service fees in advance, service is discontinued during the prebilled period, and the customer is due a refund, the following apply:

(a) A company must honor all requests for refunds of the unused portion of prepayments.

(b) If the customer provides a forwarding address to the company or one can be obtained from the U.S. Post Office, the company must issue a refund check no more than thirty days following the customer's request.

(c) If the customer cannot be located or did not provide a forwarding address and the U.S. Post Office cannot furnish a forwarding address, the amount may be presumed to be abandoned and is subject to the Uniform Unclaimed Property Act after one year.