Niagara Window Washing

Contract this company to clean my outdoor windows based on a quote of approximately $140. Was late arriving but did contact us that his team was delayed. Team cleaned every outdoor window. Window count was higher than I expected (he counts windows different than I do). Team left when windows were still wet. When they dried and in the sun, we found 5 windows with major spotting and long brownish drips. Contacted owner to return and re-do those windows. He wanted $70 to come back and correct his poor quality work, or offered me a credit for our next window cleaning. I rejected his offer because I never plan on using him again. You have to spot any problems before his team leaves else you have to pay for him to come back. How can you determine if windows are clean when they are still wet and dripping. His warranty isnt worth the paper its written on.