Tex. Water Code § 13.4115

In regard to a customer complaint arising out of a charge made by a public utility, if the utility commission finds that the utility has failed to make the proper adjustment to the customer's bill after the conclusion of the complaint process established by the utility commission, the utility commission may issue an order requiring the utility to make the adjustment. Failure to comply with the order within 30 days of receiving the order is a violation for which the utility commission may impose an administrative penalty under Section 13.4151.