All persons or corporations that are included within the definition of a "public utility," as defined in Section 58-5-10 as well as every motor vehicle carrier doing business in this State, except such as are municipally owned and operated, shall promptly, when required by the Public Service Commission, furnish to the Commission a full and detailed report and information concerning its business affairs or any matter pertaining thereto, as shall be specified in such requirement, and shall with like promptness answer fully all questions and interrogatories which may be propounded by the Commission.