Rates; adjustment.

Whenever the commission, after public hearing either upon its own motion or upon complaint, shall find the rates, rentals, charges or classifications, or any of them, proposed, demanded, observed, charged or collected by any public utility for any service, or in connection therewith, or the rules, regulations, measurements, practices or contracts, or any of them, relating thereto, are unjust, unreasonable, insufficient, excessive, or unjustly discriminatory or preferential, or in anywise in violation of law, or any service is inadequate or cannot be obtained, the commission shall determine and by order fix the fair and reasonable rates, rentals, charges or classifications, and reasonable rules, regulations, measurements, practices, contracts or service, to be imposed, observed, furnished or followed in the future.