All electric membership corporations which furnish service in the State of Georgia and all municipalities, whether incorporated by this state or not, which furnish service inside the state shall, in addition to the manner and extent otherwise provided for in this part, be subject to the authority and jurisdiction of the commission in the same manner as electric light and power companies are subject under other laws of the State of Georgia and regulations of the commission pursuant thereto, provided that the rates, charges, and service rules and regulations of electric membership corporations and municipalities shall be filed with the commission and shall be subject to Code Section 46-3-11 but shall not otherwise be fixed by the commission; provided, further, that securities issued by a municipality relating solely to service rendered inside its limits as they existed on March 29, 1973, shall not be subject to regulation by the commission; provided, further, that service rendered by any electric supplier shall be made pursuant to and consistent with its rates, charges, and service rules and regulations then in effect.