(a) If the parties have not been able to settle their dispute, the hearing officer or informal reviewer will make a written decision. In reaching the decision, the hearing officer shall give consideration to the evidence and facts of the case, and base the decision on his or her findings, applicable State law, commission rules, regulations, orders and opinions, and utility tariffs. The decision shall summarize the positions and arguments of the customer and the utility, the facts as established, the reasons for the decision, and, where appropriate, include a statement of what actions must be taken by the parties.

(b) The hearing officer or reviewer shall promptly notify the parties, by first class mail, of the decision and of the parties' right to appeal in writing to the commission and the time by which an appeal must be filed.