The Commission shall, upon not less than ten (10) days written notice to all parties, conduct a hearing on the complaint. All parties shall be entitled to be represented by legal counsel, and shall have the right to call witnesses in their own behalf and to cross examine witnesses. All parties to the proceedings may apply to the Commission to have subpoenas issued in the name of the Commission. Testimony taken at the hearing shall be under oath or affirmation, and a transcript shall be made and filed with the staff. No fewer than four (4) of the same members of the Commission must be present at all times. Only those members who have attended all hearings on the matter, or have read and reviewed all the transcripts of the hearings, shall participate in the determination of the complaint.