(a) The commission may investigate the management of a public utility, including staffing patterns, wage and salary scales and agreements, investment policies and practices, and purchasing and payment arrangements with affiliated interests, for the purpose of determining inefficient or unreasonable practices that adversely affect the cost or quality of service of the public utility.
(b) Where unreasonable practices are found to exist, the commission may, after providing reasonable notice and opportunity for hearing, take appropriate action to protect the public from the inefficient or unreasonable practices and may order the public utility to take the corrective action the commission may require to achieve effective development and regulation of public utility services.
(c) In a rate proceeding, the utility involved has the burden of proving that any written or unwritten contract or arrangement it may have with any of its affiliated interests for the furnishing of any services or for the purchase, sale, lease, or exchange of any property is necessary and consistent with the public interest and that the payment made therefor, or consideration given, is reasonably based, in part, on the submission of satisfactory proof as to the cost to the affiliated interest of furnishing the service or property and, in part, on the estimated cost the utility would have incurred if it furnished the service or property with its own personnel and capital.