(a) Any interested person on behalf of a client or a client himself if he is 12 years of age or older may object to an administrative, diagnostic or temporary admission under this Article. An objection may be made at any time following the admission, but once an objection has been heard, no subsequent objection may be made for 6 months without leave of the court.
     (b) An objection shall be submitted in writing to the facility director of the facility.