Any person may file a complaint with the Commission. The complaint shall be in writing and set forth circumstances that allege a violation of this division by a public service company. If a complaint filed under subsection (a) of this section states on its face a violation of this article or if the Commission determines that the complaint deserves an explanation, the Commission shall: serve a copy of the complaint on the public service company; and issue an order that requires the public service company to satisfy or answer the complaint in writing within a specified time. A person that is the subject of a complaint filed by any person or the Commission is entitled to a hearing in a contested case that results from the complaint. Subject to paragraph (2) of this subsection, the Commission must conduct an investigation of the matters in a complaint filed under this section if the complaint concerns the following: the quality or reliability of gas supply or electric power supply; or the price of gas or electricity. In order to be entitled to an investigation under paragraph (1) of this subsection, the complaint shall be signed by: the People’s Counsel; the chief executive or local legislative body of a municipal corporation or county in which a gas or electric company is authorized to operate; or not less than 100 customers of the gas company or electric company, with the names and addresses of the customers set out in the complaint. The Commission shall begin proceedings on its own motion against a person by filing a complaint. The complaint filed under paragraph (1) of this subsection for the first time in a proceeding shall be served on the person that is the subject of the complaint before any hearing on the matter. Unless a complaint is voluntarily satisfied, the Commission shall take final action on each complaint by issuing an order that: dismisses the complaint; directs full or partial satisfaction of the complaint; or directs any action that the Commission considers to be warranted.