Remaining level-headed and staying professional is what the interviewer is looking for in your example. Give an example of how your excellent communication skills allowed you to handle a difficult client. If you haven’t had an experience with a problematic client, explain how you would handle the situation.
"In my current position I am faced with challenging clients on a daily basis. I seem to always come to a good resolution by using my gift of gab. I ask questions and actively listen. A recent example would be when a very unhappy customer called in, wanting to speak with the manager. Our manager was away, and I was the next best person for her to speak with. By listening and accepting responsibility for the company's actions, I was able to calm her down. We came to a solution that was great for everyone, and I was sure to follow up with her actively."
"I had a client call saying that we delivered a defective piece of merchandise valued at over $30k. Understandably, he was livid. He was threatening to not only stop doing business with us but also make sure no one else in his company or his contacts in the industry would give us the time of day. This was one of my best customers, previously, so it was a rough phone call. I immediately took responsibility and asked pointed questions to try to get to the root of what was defective about the item, and assured him over and over that we would make it right. I went into a conference room, bringing the COO and Director of Ops with me, and we all assured him how we valued his business and would be sure to make it right. Not only that, we would put steps in place to ensure this type of thing did not slip through QA again. Ultimately, we had a satisfied customer who went on to grow in business volume and praised how we remedied the situation."