(a) The Commission may compel the attendance of witnesses and the production of tariffs, contracts, papers, books, accounts and all other documents.
(b) Any member of the Commission, or any examiner or employee designated by it, may administer oaths to all witnesses who may be called before the Commission, any member thereof, or any examiner, as the case may be.
(c) Subpoenas issued by the Commission shall be signed by a member thereof or an examiner designated by it and attested by the secretary, and may be served by any sheriff, deputy sheriff, constable, or any employee of the Commission and return thereof made to the Commission.