You've heard the old phrase, "there's a thin line between love and hate?" Well, successful people know the opposite is true. Intense, negative energy can be converted into positive passion. So if your business experiences a disgruntled customer, don't chock it up to "well, you win some, you lose some." You have been presented an amazing opportunity. Angry customers can become amazing advocates. You just need to adjust your mindset and adopt the right method.