Poor service at Erand Gardens

I reside at Erand Gardens 61 at ground floor. Our back yard has changed to a dumping area. Tenants upstairs party every weekend and throw beer bottles, cigarret stompies, tissues, used panty liners and cider bottle caps to our backyard. Water is also pouring from the roof next to our front door and causing mosquitos. We have been complaining a lot to securities and they advice that we need to complain to Trafalgar because they said they tried to talk to guys upstairs and they are not listening. I even took pics from my back yard, unfortunately there's no option to attach on this site. Please advice