The key to success in working with complaining clients is to train employees to communicate effectively with them, so your company needs to initiate an outstanding complaint recovery strategy. General philosophy Don't take clients' upset personally. Make it a game or challenge to see how many complaining clients you can turn around. See if you can have the conversation end with their being happy. Use a soft and soothing voice.
Most people are happy with a simple apology presented in an understanding voice.
Aim to open communication by using probing questions. If the person seems reluctant to discuss the problem, rephrase the question. Listen fully Don't interrupt or become defensive or argumentative. If you do, it likely will escalate the situation. Show you're interested and concerned.