Harassed by young adults

My father is over 72 years of age and my mother is over 65 yrs and my father is a heart patient and my mother has recently been operated upon for cataract. We have a corner home in DDA MIG Flats and there is a badminton court right next to it. Children use the badminton court to play cricket, volleyball, badminton etc and their ball constantly lands in our verandah. Initially we used to go and give the ball to the children but finally we told the children that it is not possible for me or my old parents to give them the balls when it comes every time. Some of the children even broke portion of the wall so that they could enter the verandah and recover the ball themselves. Even one of the chowkidar joined them and they used to regularly climb the fence and recover the balls. The balls have become a constant source of harassment and we have communicated this many times for almost 2 years now and yet different groups of children have been harassing us to no end. This has proved to be very difficult time for us. Recently we had repaired the walls and increased their height to reduce the chances of the balls landing in our verandah but the children started playing volleyball. We clearly told the children that they should not harass us and we will speak to the association and their parents. The children gheraoed our home and started harassing us by ringing our bells and I panicked and we were at wits end, we told them clearly not to harass us like this but they refused to listen and kept ringing the bell and we got irritated and had an argument with the children during which I slapped one of the kids who was harassing us and finally they dispersed. Later another boy came to our home and started hurling abuses and threatening me and my parents for no reason. he said he will fix us within a week. Finally the neighbours intervened and gathered outside our home. Police was called and both sides put the matter in front of the police officers. We clearly stated that we cannot be expected to be going out to verandah to give the ball to the children every time. The neighbours said that children should be allowed to play. I apologised to the boy who I slapped and the neighbours promised to look into ways to ensure that the ball does not end up in our verandah and also restrict the timings of the children. The young man who threatened me and my family did not apologise and left unrepentant. We are extremely upset and feel victimised. The children will most likely continue to harass us. They have been emboldened by the support of their parents. Please suggest a way out of this mess. Can we get a restraining order on the person who threatened us?