If calling them at 2 am for some reason doesn't get the business result you want, and you have to go to court, the court'll ask you what reasonable steps you've already tried to resolve amicably, and the judge will think you're in the wrong when your opponent brings out a log of your 2 am calls to their residential address. Suddenly it'll look like they were just doing legitimate business and you were threatening and harassing.
Even if you aren't a moral person, it pays to do things properly.