Utah Code § 54-3-7
Except as provided in this chapter or Chapter 8b, Public Telecommunications Law, no public utility shall charge, demand, collect or receive a greater or less or different compensation for any product or commodity furnished or to be furnished, or for any service rendered or to be rendered, than the rates, tolls, rentals and charges applicable to such products or commodity or service as specified in its schedules on file and in effect at the time; nor shall any such public utility refund or remit, directly or indirectly, in any manner or by any device, any portion of the rates, tolls, rentals and charges so specified; nor extend to any person any form of contract or agreement, or any rule or regulation, or any facility or privilege except such as are regularly and uniformly extended to all corporations and persons; provided, that the commission may, by rule or order, establish such exceptions from the operation of this prohibition as it may consider just and reasonable as to any public utility.
Utah Code § 54-3-7