My neighbor and his territorial behaviour

More neighbor problems today. We have a fence that separates us, that they installed. But they insist on killing any plants that are growing on the fence. They cut parts of the kiwi vine that was touching the fence, killing most of the plant. The wife said that she did it, and said she will continue to do it. They are definitely not pleasant people to us. My solution is to add a trellis on my side of the fence and visit City Hall tomorrow and have the township explain the rules to me about having a fence on the property line and what the rules of behavior are for one. When I went over to talk to them, they complained that I was purposefully turning the corner of my yard into a swamp. The corner of my yard does turn into a swamp when it rains because their rain water runs onto my property. Last year they had a PVC pipe running from their downspout onto the edge of their property so all the water would come onto my property. When I asked them to remove it they did. Last year I caught the old man, the grandfather, throwing trash into my yard. When I confronted him he said: "It probably came from your yard anyway." I said: "Is that behavior that you want to teach your grandchildren?" My solution to the water coming onto my yard is to build a berm of dirt so the water is directed out to the street instead of into my yard. I am heading to Home Depot now to get some pressure treated trellis for the grapes and kiwis to grow onto. I am hoping that will solve the problem amicably.