This happened about 2 years ago. My colleague at work, who's a kind and smart soul was actually yelling at the phone. Before that nobody had heard her yell at anyone, let alone a client.

The history was that she found out that the client sent her falsified official documents and she confronted him about that, so the idiot client started laughing then yelling that she had to be 'on his side' since he hired us as consultants. That's when she started yelling.

How can anyone be so cynical?
This is also our job to save your moron ass from your own stupidity.
If she didn't found out and the documents sent to the government there would be a lot of trouble for everyone especially the client.

After that we all comforted her and told her she did right. Unfortunately the client wasn't fired (a friend of the boss) but of course we all declined to work with that client again.