The ‘animal welfare act 2006’ says this illegal to cause unnecessary suffering to a dog by leaving it alone for prolonged periods of time.Well sadly there’s not enough people who care about neglect of a dog, as there is nothing illegal about what he is doing, nor is there an agency who can stop him.
If it is howling like you say then it is in some kind of distress. I would point this out to the council or other animal welfare authorities or point this out to your neighbour.
Get in touch with your local MP for them to get involved, you neighbour clearly couldn’t care less about the dog so I’d be telling anyone and everyone what he’s doing.
People are crazy for dogs, it won’t be long before you get someone’s ears to wick up.