If, upon a hearing and investigation had under the provisions of this chapter, the division shall find any existing rates, tolls, charges, or joint rate or rates of any public utility, to be unjust, unreasonable, insufficient, or unjustly discriminatory, or to be preferential or otherwise in violation of any of the provisions of chapters 1 - 5 of this title, the division shall have power to fix and order a substitute therefor the rates, tolls, charges, or joint rates as shall be just and reasonable.
R.I. Gen. Laws § 39-4-9