Meek, Aggressive, High-Roller, Opportunist and Chronic Complainer are the customer types that MagnifyAds outlines in this infographic.
The Meek Customer has a low “difficult to fix” and “irrational” metric, where a simple “I’m sorry” may be enough to solve the problem. The Aggressive Customer is suggested as better dealt with by taking the complaint off-line. Watch out for the Chronic Complainer, with the highest difficulty to fix and irrational metrics: