Me and DH have had long running issues with our neighbours. They are two men who rent together and they frequently have all night parties that usually go on until 3-4am. They cause us a lot of disruption but despite taking it up with the Landlord and Environmental Health nothing is being done. We've had some HUGE arguments in the past where DH and I have both reached the end of our tether but again, nothing changes.
Anyway, they had friends over again last night and when I got up this morning I saw 5 cigarette butts lying in our garden which obviously the NDN's guests have just chucked over the fence into our garden once they've finished their cigarette. I was absolutely livid!! 
I just can't believe how disrespectful it is.
I told my DH who said he would throw them back over the fence whereas I wanted to go round and confront them. Admittedly I can be a bit hot-headed at times but I don't think just throwing them back over the fence makes much of a point. Their garden is really overgrown and full of calf high weeds so the NDNs wouldn't even see the cigarette butts anyway if DH does throw them over do they won't realise we've retaliated. I don't want them to think they've got away with it and that we are too cowardly to address it.
I just feel so angry
Me and DH are in limbo.
Who is right about what action to take?
(As an aside, I posted a few months ago about parking wars with my neighbours and I just want to point out these aren't the same neighbours, these ones are joined to us on the other side).