In many customer service situations, the representatives of the company are dealing with people who are in some way unhappy with the company. Therefore, it is not surprising that the representatives' communications could cause the customers' emotions to escalate. This is particularly the case if the rep does not communicate in a way that shows sympathy for the customer.
Many times, customer service representatives are not really able to give the customer what he or she wants because it may be against the company's policies. When this happens, it is important for the rep to be very skillful in handling the communication. They are having to give the customer bad news and that is very hard to do without escalating the customer's emotional state.
Because customer service reps are often delivering bad news, it is easy for customers to become more upset. Therefore, the communications from the reps can easily escalate the customers' emotions unless they are done with great skill.