Final answer:
Being placed on hold for a long time and being transferred repeatedly are two factors that frustrate customers in terms of customer service.
Step-by-step explanation:
In the context of customer service, two things that most frustrate customers are being placed on hold for an extended period of time and being transferred repeatedly. When customers are placed on hold for a long time, it can make them feel ignored or unimportant, leading to a negative experience. Similarly, being transferred multiple times can be frustrating as it often involves repeating information and wasting time. To provide excellent customer service, businesses should aim to minimize hold times and ensure that transfers are done efficiently and effectively.