Our landlord won't give us enough heat!?

There are six tenants in this building, ranging in ages from early 20s-late 90s. In the winter, most of the time the heat is at least 68F but often more. The problem is on the days/nights it gets to 0F or below; then the pipes bang because the heat is so low and the apartments get down as low as 60-62F. People sit in their apartments with gloves and coats on. When tenants complain, he replies, "It's an old furnace; I can't do anything about it; it's up as far as it will go", which we all know is a lie. I know this is illegal, but exactly who can I call to complain to so that this bastard will be forced to turn up the heat? Can anything be done?