We have tried the neck zappers for the sheltie and she quickly learned the tolerance of the zapper and barked just enough not to get zapped. Your help would really be appreciated by our neighbors. The only thing that you have tried that I would not have recommended was the use of a shock collar. Regardless of what they are called, I believe they are inhumane, and they only tend to cover up underlying problems rather than correcting them. Let's look at some of the reason why dogs bark.
Dogs use barking as one way to communicate.
They bark to express needs, to gain attention of their pack, and to stake out their territory against just about anything that crosses their path. The reasons for this vary. One of the main reasons dogs nuisance bark is that they are isolated from their pack. Like their ancestors, the wolves, dogs are pack animals. And your dogs consider you and your family their pack.