Unless otherwise ordered by the Commission, a public service company may not establish a new rate or change in rate unless the public service company: provides to the Commission notice of the new rate or change in rate at least 30 days before the new rate is established or current rate is changed; and publishes the new rate or change in rate in accordance with § 4–202 of this subtitle during the entire 30 day notice period in new schedules or plainly indicated amendments to existing schedules. The public service company shall plainly set forth in the notice and publication: the changes that it proposes to the rate schedules currently in force; and the effective date of the changes. The technical staff of the Commission may assist a water company or a sewage disposal company in establishing a proposed just and reasonable rate. In assisting a water company or a sewage disposal company under this subsection, the technical staff may seek information from the water company or the sewage disposal company. The Commission shall restrict the availability of staff–assisted rate cases authorized under this subsection to water companies or sewage disposal companies whose gross annual revenues, for the most recent calendar year for which data are available, are below an amount determined by the Commission, not to exceed $1,000,000. The Commission shall adopt regulations to establish formal rules for staff–assisted rate cases authorized under this subsection.