Bill Gates said, "Your most unhappy clients are the greatest source of learning."
Customer may transmit a requested or unsolicited feed-back about a brand or products, its services through several methods, the important thing is to give them obedience. Customer complaints are the most relevant source of "pain" of the system, which can be translated into improvement ideas. When a company receives a significant number of complaints on a particular topic, it is very clear that there is a problem. Moreover, the important perception point (touchpoint) has been identified for the customer.
Let's take as an example, customer service from a bank. If clients constantly call and complain that they do not receive the credit card statement on time, the bank should understand that the customer is important predictability and financial information on his or her account. In This situation, the bank should resolve the issue of the account statement and surprise its clients with an SMS information service of each transaction it makes and the amount available on the credit card.
Complaints help companies improve products, processes, and employee attitudes. From my point of view, including the CEO and top managers should have listening sessions or analyzing complaints, to feel the customer experience.