As we first attended site with cityflex unit, crew found blockage on carrier drain serving block of flats. All waste from upstairs flat discharging into clients flat. Crew rapidly located blockage and cleared. CCTV survey identified mass roots as cause of re-occurring blockage, position of roots located using radio detection unit ready for Civils crew to excavate and remove roots and repair damaged pipe work. Specialist clean up crew attend site following blockage clearance and commence clean up. Within 4 hours apartment cleaned and works complete.