R.I. Gen. Laws § 39-3-13.1
The division shall have the power, when deemed by it necessary, to provide remedial relief from unjust, unreasonable, or discriminatory acts, or from any matter, act, or thing done by a public utility, which matter, act, or thing is in chapters 1 - 5 of this title, or otherwise, prohibited or declared to be unlawful, to order the public utility to make restitution to any party or parties, individually or as a class, injured by the prohibited or unlawful acts, by way of a cash refund, billing credit, or rate adjustment, or any other form of relief that the division may devise to do equity to the parties. Any award made in restitution shall carry interest from the date of the injury, at the rate of seven percent (7%) from the date of the order of the division.
R.I. Gen. Laws § 39-3-13.1