why don't you just have words with the neighbours , tell them what the problem is and how its making you unhappy , suggest to them that you would gladly help them resite it a bit further from your fence where you suggest ?? if its suitable, no neighbours want to be on confrontation with each other if at all possibe, try it before going down the one way street to solicitors and council officials , if all else fails , just grit your teeth and stop moaning , they will be soon back at school !