Blatantly doing mischief

My neighbour in the backside throws garbage in my property. I have meet with him many times he always says he will not do it again but his children always do everytime so, I decided to cover the area from my side using metal sheets but still I have a small boundary he throws off through that and uses the boundary as hanger for his mats. I tried approaching him knocked his door tried to talk to him that I cleaned this mess 3rd time but his wife came I asked her to call Mr. abc. she said I can tell her what is the problem I explained her that this is my 3rd time cleaning this she immediately replied that I was thinking to big your boundary to certain height. I will think about it she said it's better to increase the height of the wall no one will throw it. I didn't replied I said call Mr.abc I will tell him she said you told me that's enough I'll tell him build the wall get to some good height. We have already spend more than 15k covering up the area.