(a) Whenever an investigation is undertaken by the public utilities commission, reasonable notice in writing of such fact and of the subject or subjects to be investigated shall be given to the public utility or the person concerned, and when based upon complaints made to it as prescribed in section 269-7, a copy of the complaint, and a notice in writing of the date and place fixed by the commission for beginning the investigation, shall be served upon the public utility or the person concerned, or other respondent and the complainant not less than two weeks before the date designated for the hearing.(b) Any notice provided pursuant to section 269-16(b), shall plainly state the rate, fare, charge, classification, schedule, rule, or practice proposed to be established, abandoned, modified, or departed from and the proposed effective date thereof and shall be given by filing the notice with the commission and keeping it open for public inspection.(c) Any public hearing held pursuant to section 269-16(b), shall be a noticed public hearing or hearings on the island or islands on which the utility provides utility services. Notice of the hearing, with the purpose thereof and the date, time, and place at which it will open, shall be given not less than once in each of three weeks in the county or counties in which the utility provides utility service, the first notice being not less than twenty-one days before the public hearing and the last notice being not more than two days before the scheduled hearing. The applicant or applicants shall notify their consumers or patrons of the proposed change in rates and of the time and place of the public hearing not less than one week before the date set, the manner and the fact of notification to be reported to the commission before the date of hearing.L 1913, c 89, §10; RL 1925, §2198; RL 1935, §7950; RL 1945, §4711; RL 1955, § 104-11; HRS § 269-12; am L 1983, c 98, §1; am L 1991, c 57, §8; am L 1998, c 2, §81; am L 2009, c 29, §2 .