Most of the difficult customers we encounter are either unsatisfied customers who are acting badly, or customers who have unrealistic expectations of you or your company. The vast majority of these customers can be won over with the use of some fundamental effective and positive strategies.
There are some customers, however, with whom these strategies don’t work. There are some who exhibit such extreme behavior that very specific action is required. Such is the case with the threatening customer.

With a customer who physically threatens you, there is only one appropriate action, and that is to remove yourself from the situation immediately. Don’t explain yourself; don’t threaten back; simply say, “excuse me,” and leave to find someone in authority. Whether the authority is your boss or the police, it is they, not you who must deal with this customer.

Is this being overreactive? No. While physically threatening customers are extremely rare, their very aggresive nature makes them unpredictable. I’ve heard far too many horror stories of employees who wished they hadn’t ignored the warning signs.

If the customer threatens you in a non-physical manner, eg: “I’m going to see to it that you get fired,” the only consistently effective response I know is silence. Again, these customers and situations are quite rare, but you don’t want to risk saying or doing anything that might escalate the situation.

I truly hope that you never have to deal with customers like these in your career, but if you do, take care!