When petition has been made to the commission concerning any rate or charge for service performed by any telephone utility, and the commission has found after hearing that the telephone utility has charged an unreasonable, excessive, or discriminatory amount for such service, the commission may order that the telephone utility make due reparation to the petitioner therefor, with interest from the date of collection, if such reparation will not result in establishing unreasonable discrimination. No order for the payment of reparation upon the ground of unreasonableness shall be made by the commission in any instance wherein the rate or charge in question has been authorized by law. All petitions concerning unreasonable, excessive, or discriminatory charges on which reparation orders may be made shall be filed with the commission and provided to the Office of Regulatory Staff within two years from the time the cause of action accrues. No assignment of a reparation claim shall be recognized by the commission except assignments by operation of law as in case of death, insanity, bankruptcy, receivership, or order of court. The commission must not be a party to any reparation action.

The remedy in this section provided shall be cumulative and in addition to any other remedy in Articles 1 through 13 of this chapter provided in case of failure of a telephone utility to obey an order or decision of the commission.