Upon a complaint made and filed by any municipality, or by any person or party affected, that any rate, service regulation, classification, practice or service in effect or proposed to be made effective is in any respect unfair, unreasonable, unjust or inadequate, the commission may proceed, if the commission finds probable cause for said complaint, and without such complaint, the commission, whenever it deems that the public interest or the interest of consumers and investors so requires, may proceed, to hold such hearing as it may deem necessary or appropriate; but no such hearing shall be had without notice, and no order affecting such rates, service regulations, classifications, practice or service complained of shall be entered by the commission without a hearing and notice thereof. Any utility may make complaint as to any matter within the provisions of this act affecting it.