If I am dealing with a angry customer, I would remain calm and stay focused to resolve their issues. I will actively listen to that customer without interrupting. Because it is important to allow customer to vent their frustrations fully. I will empathize with there concerns by saying something" I can feel how frustrating it must be for you" it will make them feel that I am acknowledging their concerns. Then, I will apologize if necessary. For example, if the error or the problem from our side, I will sincerely say sorry, even it's wasn't directly my fault. I will clarify the whole problem by repeating the key points, so that I know I am on the same page with the customer. I will offer every possible solution from my side to resolve the issue, if the issue is beyond my ability then I will escalate the call in the right department to make customer feel that their concerns are being handled with urgency. I will take follow up from customer after the issue get resolved