A few weeks ago, in anticipation of our impending flooding I had a my sump pump replaced. Friday I received the invoice in the mail. One line had and price of the sump pump. The next line had 2 hours labor X $95/hour. The repairman was barely here 1/2 an hour. When I called that day, she said it also took into consideration time since he left their shop and returned. I said I understood that but didn't see how that could be 2 hours. Yesterday the service manager called me back and said they had been charging a flat rate of the original amount of the bill (the total with the $190 of labor). I said that would be fine, but when you have it considered 2 hours of labor for less than an hour's work. So he deducte the $95. So with one phone call I saved myself $95.
This also stresses the importance of checking charges on your credit card statements. To be sure there hasn't been a mistake.