Action by the Planning Commission. Testimony given during the appeal shall be limited to those points cited in the appeal application. The planning commission shall render a written decision on the appeal within ten business days from the conclusion of the hearing unless a longer period is mutually agreed to by the appellant and the planning commission. The planning commission may affirm, reverse, wholly or in part, or modify the order, requirement, decision, or determination, and to that end shall have all the powers of the officer from whom the appeal is taken. The department shall send copies of the planning commission's decision to the appellant, the parties of record, and the official whose decision was appealed not later than three business days following the issuance of the final decision.