North Carolina General Statutes Chapter 62. Public Utilities § 62-139. Rates varying from schedule prohibited; refunding overcharge; penalty

(a) No public utility shall directly or indirectly, by any device whatsoever, charge, demand, collect or receive from any person a greater or less compensation for any service rendered or to be rendered by such public utility than that prescribed by the Commission, nor shall any person receive or accept any service from a public utility for a compensation greater or less than that prescribed by the Commission.

(b) Any public utility in the State which shall willfully charge a rate for any public utility service in excess of that prescribed by the Commission, and which shall omit to refund the same within 30 days after written notice and demand of the person overcharged, unless relieved by the Commission for good cause shown, shall be liable to him for double the amount of such overcharge, plus a penalty of ten dollars ($10.00) per day for each day's delay after 30 days from such notice or date of denial or relief by the Commission, whichever is later. Such overcharge and penalty shall be recoverable in any court of competent jurisdiction.