Is it possible that you misunderstood them, or they misunderstood you?
With your client, employee, vendor, partner, or that random passerby?
The thing that just happened, it sounds terrible, and if they did it on purpose, the way it sure seems to you and to me, that would be horrible.
But before we burn down bridges and ruin everyone's day, just a quick moment to wonder, "what if there was something misunderstood?"
It's a lot easier to ask than it is to go to all the trouble of breaking things.