No public utility shall, directly or indirectly or by any special rate, rebate, drawback or other device or method, make any deviation from the rates, fares, charges or prices for any service rendered by it specified in its schedules on file and in effect at the time such service was rendered.
Source. 1913, 99:2. PL 242:21. RL 292:22. 1951, 203:46 par. 21, eff. Sept. 1, 1951.