Concerned about graffiti, weeds

Is the city above the law? A few years ago the city council passed an ordinance that said if somebody reported that you had graffiti on your property you had to remove it within 24 hours. I have called the nuisance officer, the street department and my councilman about graffiti and weeds 2 to 3 feet tall along the sidewalk on the 3rd Avenue viaduct. Nothing has been done about it. Some of the graffiti has been there since last summer.