Construction of Temporary Structure on Boundary of Land

I live in an Approved Layout. On the Right side of my house, my neighbour has constructed a temporary structure by raising a 11 ft wall on boundary and has placed a Metal Sheet Roofing. He is using that temporary structure for storing various kind of scrap that remains from every fabrication he does as he is a engineering fabricator/contractor. On the Other side of his plot(adjacent to road) he has constructed a small house again on the boundary. He has left the middle portion of plot empty. I have 2 coconut trees placed 5 feet away from the boundary. While he raised a 11ft wall on boundary 5 years back, i objected it mentioning that the coconuts would fall on his sheet as its in boundary and my house will loose ventilation and sunlight and it will disturb my peace of living. He said that he will only place a metal sheet roof and nothing would damage his sheets. The coconuts while falling down would make noise and we were disturbed. Now after 5 years he has now began to quarrel disrespectfully asking us to cut down our trees. We feel that he is planning to construct a regular RCC Roofed building on the boundary now. Please advice me on the authorities that i should write to and to apprise of the deviations that he has made in his constructions and now harassing us. We own the land for 35 years now and he is talking in abusive language and trying to ill-treat us. Am a senior citizen and i feel very disturbed through his behaviour.