The said Commission shall have power, and it is hereby made its duty, to investigate all through freight or passenger rates on railroads in this State, and when the same are, in the opinion of the Commission, excessive or levied or laid in violation of the Interstate Commerce law, or the rules and regulations of the Interstate Commerce Commission, the proper officials of the railroads are to be notified of the facts and requested to reduce them or make the proper corrections, as the case may be. When the rates are not changed, or the proper corrections are not made according to the request of the Commission, it shall be the duty of the latter to notify the Interstate Commerce Commission and to make proper application to it for relief, and the Attorney General or such other persons as may be designated by law shall represent the Commission in all such matters.