There is a gap under the fence between me and my neighbour. It's his fence. He keeps pushing garden waste, clippings, clumps of dead grass etc, under the fence into my garden. I have tried blocking up the gap with bricks, and he just pushes them out the way. I can't talk to him as he's an aggressive bully. I know he's doing it on purpose. What can I do about it and AIBU to let it bother me?