Any person, firm, association of persons, corporation, municipality or county, complaining of anything done or omitted to be done by any public utility subject to this chapter, in contravention of the provisions thereof, or any duty owing by it under the provisions of this chapter, may present to the commission a petition which shall succinctly state all the facts. Whereupon, if there shall appear to be any reasonable ground to investigate such complaint, a statement of the charges thus made shall be forwarded by the commission to such public utility, which shall be called upon to satisfy such complaint or to answer to the same in writing within a reasonable time to be specified by the commission. If such public utility within the time specified shall make reparation for the injury alleged to have been done, or correct the practice complained of and obey the law and discharge its duties in the premises, then it shall be relieved of liability to the complainant for the particular violation of the law or duty complained of. If such public utility shall not satisfy the complainant within the time specified, it shall be the duty of the commission to investigate the same in such manner and by such means as it shall deem proper.