The plastic outlet from my kitchen sink goes out through the kitchen wall and into an elbow joint and then a straight pipe down to the grid. The elbow joint has weathered to the point it has worn through/ disintegrated and needs to be replaced. I thought it might be a simple diy job so bought a new elbow joint but when I've tried to fit if, Ive realised that ,where the old one has broken off, the bit that pushes inside is still in place so I can't push the new elbow joint in. I've tried to disconnect from the inside. I can undo the u bend, but I can't undo the elbow joint that goes from the u bend to the straight piece of pipe that goes through the wall. So I'm admitting defeat and calling in a tradesman. But who do I need, a builder or a plumber?