How to deal with neigbours kids jumping over our fence

Hey guys just want some advice on what i can do to stop my neighbours kids from jumping over our fence to grab their balls, we've been dealing with this for a while now and can't get them to stop. We got a dog but unfortunately the dog doesnt scare them as where they'd jump in would be protected by a pool fence, we've recently had a chat with one of the boys which we caught in the process and he says that when they call for the ball we never answer which i understand to an extent but i tried to get him to understand that the fence has slowly been leaning to our side of the house due to them always kiciking the ball at our fence and climbing over it, i tried to let him know that if he'd be okay with walking by our house we would give it him his ball without any hesitation but he said the walk was too far (2min walk) and that "he's alright", his parents do not care at all because we had a chat over it and the mum would be supporting the sons behaviour by gaslighting that we were in the wrong for not returning their ball.