The Commission shall approve or disapprove a plat within 45 days after the submission thereof; otherwise such plat shall be deemed to have been approved and a certificate to that effect shall be issued by the Commission upon demand. Such period may be extended by mutual agreement between the Commission and the applicant for the Commission's approval. The grounds of disapproval of any plat shall be stated upon the records of the Commission and a copy of such statement shall be furnished to the applicant. No plat shall be acted upon by the Commission without affording a hearing thereon as outlined in § 6812 of this title and notice of the time and place of which shall be sent by registered mail to such applicant not less than 5 days before the date fixed therefor. Any approval or disapproval may be appealed to the county government within 30 days of the official action of the county government.