When customers are mad at your company, this is your big opportunity to make amends and turn these currently dissatisfied customers into raging evangelists for you. Some companies can earn deep customer loyalty when the tough times come in the relationship. Other companies just seem to mess it up even more. Success or failure depends upon how they handle the situation. You must have a customer service culture that welcomes all hard to hear feedback and criticism. In fact, you must train your customer service agents to ask for feedback and not be afraid of it.
If your company did wrong, the customer service department should be the first to know. The agents should be coached with a script so there is a consistent message. Every related phone call should begin with a heartfelt apology. Are you more or less likely to forgive a company that proactively takes full responsibility for short comings? Also, your company should consider immediately reaching out to customers before they call. This is not the time to think about minimizing costs. Your company must think about making an investment to win a popularity contest. You must think, "Amaze and Delight!"
Here is a great White Paper on Customer Service Best Practices-What Features and Functions to look for in Customer Service Software.