The City Council may, from time to time, on its own motion or on petition, amend, supplement, change, modify or repeal by ordinance the boundaries of districts or regulations or restrictions herein established. Any proposed amendment, supplement, change, modification or repeal shall first be submitted to the City Plan Commission for its recommendations and report. If the City Plan Commission makes no report within thirty (30) days, it shall be considered to have made a report approving the proposed amendment, supplement, modification, or change. Upon the filing of the recommendations and report by the City Plan Commission with respect to any proposed amendment, supplement, change, modification, or repeal, the City Council shall proceed to hold a public hearing in relation thereto, giving at least fifteen (15) days' notice of the time and place of such hearing, which notice shall first be published in a newspaper having a general circulation in the City of Charleston.