20. The Régie, of its own initiative or at the request of any interested person, may(1) examine the expediency of amending a tariff and, where expedient, require a distributor to submit a proposal of amendment;
(2) determine the rate of return of a distributor;
(3) determine the cost of service allocation method applicable to a distributor;
(4) formulate general principles for the determination and application of tariffs fixed by it.