I called a plumber out today as it appears to be an issue with the pump. However, he had trouble locating the pump. He reckoned it was under the floor boards on the landing. So I had a look and found this. Is this a pump?
It has three wires going into it and it sits on a piece of wood which runs diagonally. Could there be a pipe in side it?
Just so's you know; that's an electrical junction box.