The commission shall have the power to investigate all existing or proposed interstate rates, fares, tolls, charges and classifications, and all rules and regulations and practices in relation thereto, for or in relation to the transportation of persons or property or the transmission of messages or conversations, where any act in relation thereto shall take place within this state; and 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 supplementary thereto, or of any other act of congress, or in conflict with the rulings, orders or regulations of the interstate commerce commission, the commission may apply by petition or otherwise to the interstate commerce commission or to any court of competent jurisdiction for relief.