How to deal with uncooperative neighbour

Please assess the following situation and give a remedy. 1. We have constructed a house in village. The house was constructed around the year 2000. Unfortunately the neighbours were of the same "caste". 2. The said neighbour and us have a compound adjacent (it was constructed by them way before we arrived). But the compound has holes in them intentionally. The area is slope like, so rainwater from their side ends up in ours. 3. When my father confronted with the issue years back, they replied with a shameless response that the water will flow down anyway. Moreover, a part of wall is collapsed, the neighbour did say he would get it repaired years back but till now, no progress has been made. The neighbour is not a man of his word even though he is a retired bank official and now works as lic agent. 4. The main issue is during rainy season, our land gets clogged up with water due to overflow of water from their side as well. It is highly inconvenient to us. 5. My widowed mother does tell them to repair the wall, but they do not pay heed to her words. 6. Its been 18 years, is there any harsh legal action that can be taken against them? Can we sue them? Can we complain in police station? P.S. now we don't give a weight to being of same caste anymore(enough is enough).