How to solve customer complaints?

Always keep a calm voice, give accurate consistent advice even if they don't like the answer. Apologise that they feel they had a bad experience and not for the service or action unless there was actually a fault. If you did do something wrong apologise for it acknowledge that the client suffered an inconvenience or cost because of you. Fix the problem. Learn from the problem so that it doesn't repeat.

Try to remain clam when dealing with a complaint-even if the costumer becomes irate or confrontational. Your ultimate aim is to turn their experience into a positive one. But arguing back will only make the solution worse. Thank you