If an explanation attempts to deny the complainant's experience of events, it is unlikely to be accepted. Explanations can also degenerate into a form of making excuses. The other side of the coin is that dissatisfied people may not complain if they feel nothing will happen as a result. From your own particular perspective, complaints can be used positively to improve services. The contribution that complaints can make in this way is now part of the conventional wisdom of quality management.
Complaints can help identify or confirm individual or system problems.
The damage done to the reputation of providers by not responding adequately to complainants has been demonstrated in other service sectors, as have the positive views generated by good complaints handling. Even out of pure self interest, there should be an interest in satisfying complaints to avoid protracted correspondence and unnecessary litigation.