Any State, municipality, or State commission complaining of anything done or omitted to be done by any natural-gas company in contravention of the provisions of this chapter may apply to the Commission by petition, which shall briefly state the facts, whereupon a statement of the complaint thus made shall be forwarded by the Commission to such natural-gas company, which shall be called upon to satisfy the complaint or to answer the same in writing within a reasonable time to be specified by the Commission.