回複：回複：地下室灌了水

I don't agree with some of what old-cat said,

They must have liability coverage. That can be used to cover your losses.
However their insurance company will never admit your neighbour has the liability, because they don't want to pay. So the simplest thing to do is to contact your insurance company and let them contact your neighbour's insurance company. Your company should have experienced lawyers to fight against them (otherwise, you insurance company would have to pay).