Awful mess

Could someone tell me which government agency I can complain to about the rubbish which is created, and the street cleaners time that is wasted, by the real estate agents who every weekend fix their large paper and cardboard advertisements to every lamp-post and handrail along the entire length of Sui Wo Road, in Fo Tan, New Territories? These ads only last half a day at the most, because they are washed off by the rain or blown down by the wind causing an awful mess along the whole road. Is this type of environmentally unfriendly advertising illegal, and if so when is someone going to stop it? DUNCAN LIGHTFOOT New Territories