I have a dog situation that I'm not sure how to handle...?

I live in a small neighborhood, and my neighbors across the street from me have a dog named Mojo. He's an older dog and he's fairly small. They don't mistreat him overtly, but they go on work trips for days - sometimes a whole week - at a time. He is left there completely alone, outside. He has an automatic feeder and a big bowl of water, and he can go under the porch if it rains. But dogs aren't supposed to be left alone like that for such long periods of time - dogs are companionship animals. He sits over in the yard and cries and howls while they're gone, and I walk over to see him as much as I can so he doesn't feel quite so alone. He also barks constantly during the night and keeps us - and OUR dogs - awake. We have called their landlord and notified them of this problem multiple times, and nothing ever gets done about it. I don't know what to do - if I call animal control, they'll put him down. There aren't any no-kill shelters in this area that we can contact about the problem. Any suggestions are welcomed...I'm really at a loss here.