Great quote from Valeria Maltoni:
Complaints are symptoms. Only 2% of the population — or even less — bothers to say something, anything. Which leaves the business with a false picture of what customers experience.
Those few customers that bother to complain are your most valuable assets. They are your early warning sign. You need to take them seriously, because they may be speaking for a mass of unhappy customers.
Remember, silence isn’t satisfaction. Most unhappy customers don’t care enough about you to tell you how to save the relationship. They’re just going to leave you.