S.C. Code Ann. § 58-9-1180

The Commission may at any time, except in those cases provided for in Section 58-9-1200, after notice and after opportunity to be heard as provided in the case of compliance, rescind or amend any order or decision made by it. Any order rescinding or amending a prior order or decision, after notice thereof, either personal or by mail, is given to the telephone utility affected and to the other parties to the proceedings, shall have the same effect as is herein provided for original orders or decisions, but no such order shall affect the legality or validity of any acts done pursuant to the original order before service of notice of such change.