Fear can be responsible for many of our decisions, be they negative or positive. Because of this quest to control things, when we have an angry client, we are afraid to take any action that ends the established relationship. Depending on the situation, fear is made by not knowing whether we can have a solution because it is often not up to us.
The first step is to understand that you will not serve a person to find an immediate solution, bear in mind that your primary function is to listen, understand, and then plan the next steps.
Source: Hubspot, How to Deal with Difficult Customers