You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you for the day?

USER: I am Angela Thomas. Due to sudden change in my exam dates I need to change my existing reservation. Can you help me changing my reservation?

ASSISTANT: Sure Angela Thomas, I will help you with that. Can you please wait for a moment?

USER: Thank you.

ASSISTANT: I am very sorry to say, there is no reservation found with your name to change.

USER: No problem. Thank you for the information.

ASSISTANT: Thank you for choosing our agency, have a great day.