If, after a suspended schedule has been put into effect pursuant to § 49-34A-17, the rates are finally determined to be excessive, the commission may, as an alternative to ordering an immediate refund, reduce future rates that would otherwise be charged to offset such excessive rates; or as an alternative order that a credit on future electric or gas bills be given to all consumers based on the proportionate electric or gas bills paid by all consumers in the month prior to such order being entered.
SDCL 49-34A-22