The Commission may investigate all existing or proposed interstate rates, fares, tolls, charges and classifications and all rules and practices in relation thereto, for or in relation to the transportation of persons or property, when any act in relation thereto shall take place within this State. When the same are, in the opinion of the Commission, excessive or discriminatory or in violation of the act of Congress entitled "An Act to Regulate Commerce," approved February 4, 1887, and the acts amendatory thereof and supplemental thereto, or of any other act of Congress, or in conflict with the rulings, orders or regulations of the Interstate Commerce Commission, the Public Service Commission may apply by petition or otherwise to the Interstate Commerce Commission or to any court of competent jurisdiction for relief.