In the event the commission fails to set up a petition for amendment for public hearing within twenty (20) days after its proper filing with the commission at a regular scheduled meeting, or, if after public hearing, the commission fails to recommend that this title be amended in accordance with such petition for amendment, such failure shall be deemed the final determination and decision of the commission. The final determination of the commission may be appealed to the city council, provided a written request for a hearing before the city council is filed with the mayor and a copy of such request is served on the chairman of the commission within fifteen (15) days after the final determination of the commission. (1990 Code § 12-397)