I had terrible problems with footballs coming over the fence at one time. Had a football belted so hard it landed in an upstairs bedroom window (I was sitting at desk in room). Another came flying in conservatory door knocking coffee out of my hand and then the final straw, ball came over and hit my 2 year old GC on head kicking her over. I went mad with next door, highlighted if I had wanted to I could have charged them for all the damage to planting, young trees, all still had price labels on them. Any other incidents would be reported as harassment. The inconsiderate football behaviour stopped. I pointed out too, one of my brothers was a professional footballer, played for country and he was never allowed to play with a football in the garden when he was young. Waste of time unless you gave one tgey size of a football pitch apparently. Stayed friends with neighbour once she realised the danger and nuisance her kids' behaviour was causing. I would tell the kids you will return the ball over the fence when it is convenient for you to do so and that you are not going to be sitting watching for when it comes over. Perhaps they will learn a bit more ball control if they have to wait.