To be patient and calmeven if your client is not, because if you show aggression towards him, it will only increase his anger and you risk losing all professional credibility.
Showempathy, active listening is a way to show your empathy. Thanks to this it will be easier for you to understand the customer’s point of view. You will then be in a better position to help and soothe him.
Watch your para-verbal attitude. That is, the tone you use, the pace and volume at which you speak. Speaking fast and loud will not help the client calm down. Remember that the verbal represents only 7% of your communication and that the para-verbal represents 38%. If you are often told that you can be heard smiling on the phone, it is not for nothing.