When a client is calling with an issue, and he's upset, our reflects would be to be the same upset and start blaming the client blame someone else, looking for excuses or run away. Don't do it. Try to be assertive, don't become passive aggressive. being assertive means being confident, take responsibility and solve the situation without getting aggressive, actively or passively aggressive. I mean, so, how you do it, you look for a solution and solve the issue that it is best for everyone. being assertive is about showing empathy.
Imagine how you would feel if you were in the position of the other person. I know it's not easy. assertiveness is hard work, but it pays out. It will strengthen The relationship you have with your client. It will make you happier, more confident. You will have a happier freelance life and you will work better after that.
And you will keep your client and he will come back for more and refer you to more possible clients. assertiveness will not only have you dealing with clients, but it will also positively influence your private life. If you're assertive in your family life that's solving a lot of issues. If you want to know more about assertiveness, I suppose take a training. Find local coaches who train on assertiveness or read the book, how to be assertive in any situation. That is a great great start.