Which gov't body to contact?

So here’s the deal. I own a bushiban (yeah, yeah, let the snide, snarky comments begin) and my school is in the first floor of an apartment building. From the day we’ve owned this place, we’ve had a problem with water seepage from the floor above us. Their pipes have some serious leaking going on. It leaks through our ceiling (the standard concrete type) and seeps down into the walls. We’ve had numerous plumbers and the like try to fix this problem, originally thinking it was a problem with our pipes. They’ve all said the same thing: It’s coming from upstairs. Now here’s the catch. The tossers upstairs absolutely refuse to allow anyone into their place to check their pipes and refuse to do anything about the leak themselves. We asked them many, many times to at least let the plumber have a look at the pipes, but they flat out refuse. We’ve tried to fix the problem by going at it from underneat the pipes, but at best it’s always been a temporary fix. Now, the ceiling is once again dripping water, the walls are so damp with water that the nice fresh coat of paint we put on can’t dry and has been completely ruined and we are unable to use our biggest classroom.

So, is there any government body we can get in touch with who can force the people upstairs to do something about this? I’m having visions of the ceiling collapsing over Chinese New Year or some other horrid situation arrising. Any help/advice would be greatly appreciated.