We bought a property with a flying freehold belonging to next door. They have a window over our dining room. On moving in we discovered they have a bathroom in this room and their toilet downpipe and the bath, sink and shower waste pipe (which is an open drain) are outside our door to the yard and is on our side of a high boundary wall. They are used entirely to service their ablutions! Can this be legal? They have another bathroom on their ground floor with their own drains. We only have the small back yard to sit in and it's not very nice to hear and see all their waste! Can we make them remove these pipes?