The commission, upon its own motion, may, and, upon a petition for a valuation or revaluation of the property of a public utility, including necessary audits, for the purpose of determining the rate to be charged for the service rendered, signed by twenty-five percent of the patrons or customers of such public utility, shall, endeavor to arrive at a reasonable rate through negotiations with the public utility. If within thirty days after the filing of the petition, or within    thirty days after the adoption of an order or resolution by the commission on its own motion, they are unable to agree upon a new rate which shall be not less than fifteen percent less than the rate in force at the time of the filing of said petition, or the adoption of the order or resolution, the commission shall proceed with a valuation or revaluation of the properties of the public utility involved in the manner provided by this chapter. Each person, firm, corporation, or limited liability company receiving service is to be considered a patron or customer within the purview of this chapter, regardless of the number of meters owned, rented, or used by such person, firm, corporation, or limited liability company, but a firm shall be considered a separate entity from the individual members thereof.