All acts of the Council or of any other branch of the City government affecting the City plan or involving the duties of the Commission as set forth in Section 115 of this Charter, shall be submitted to the Planning Commission for report and recommendation.  The Commission may, of its own volition, submit to the Council its recommendation on any matter which in its opinion affects the plan of the City.
   Any matter referred by the Council to the Planning Commission shall be acted upon by the Commission within thirty days of the date of reference unless a longer period of time be specified in the resolution of Council in making such reference.  No action by the Council involving any of the matters set forth in Section 115 of this Charter, shall be legal or binding until said matter shall have been referred to the Commission and until its recommendations thereon shall have been presented to the Council, unless the Commission shall have failed to present its recommendations to the Council within the time specified.