Hello,
I have very similar neighbours,
they do not care about anyone but themselves, their kids chuck rubbish over the fence, water bombs during summer sit on our shed roof(which backs on to the fence), especially when we are having a bbq,, etc etc
in the end i found that the only way they understand (talking completely useless) is to actually do the same back,
ie: chucking more rubbish back over the fence,
covering the shed roof with grease,
and the best one ordering loads of stuff via mail order to their address