Harassing neighbour

I am having a house which is having 1 street and 1 Main road , i have open a shipon the road side and house gate on street . Neighbour's house and our house make a L , left side is neighbour house and bottom side is our house | _____________ |. | |. |. |. | |. |. |. | |...............|____________.|. | |______________________. | |. | |. | |. | This is for your better understanding, thing which is closed by all side is small part of street that they use of garden Rest part they use for their parking area Dotted line is like they make sort of imaginating boundary , boundary's other side whole area is his area, if by any chance our bike goes there side , they start shouting, one day by mistakely our bike goes on their a little, but he took my bike and park it on middle A very tight lane , they left for going on our side Their ac s also on our side , water keeps coming from that side and damaging are wall Whenever we wake up there is so much after in front of our house, Also every morning they throw so much water to clean their by saying they cleaning their side All the water is collected in front of our Could you please tell what can I do