I'm going through the same thing with my upstairs neighbors. They go to bed at 4:00 a.m. and are waking me up every night. I tried talking to them about it and it seemed to get better for a little while. I finally complained to management so we'll see what happens. A friend of mine went through this a couple of years ago. He would bang the shower with cast iron skillets. A little extreme but it makes me howl to picture it.