Had quite a few clients that had problems like that, either they were too busy or spoiled their dogs usually though. Positive reinforcement's the best method imo, it reduces miscommunication and is a mutually beneficial relationship, but you've gotta be able to find a treat (food/attention generally) that works and keep it exclusive enough to be worked towards.

Its not a lack of being let out enough. He panics then pisses for no reason. I'm quite literally at the end with him.