The commission may at any time, upon notice to the corporation affected, and after opportunity to be heard as upon a complaint, rescind, alter or amend any order or decision made by it. When the order making such rescission, alteration or amendment is served upon the corporation affected, it is effective as an original order or decision. In all collateral actions or proceedings, the orders and decisions of the commission which have become final shall be conclusive.
A.R.S. § 40-252