You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I aid you?

USER: I am Andrew Lewis. I want to change my existing reservation due to sudden postpone of my exams. Can you help me with that?

ASSISTANT: Sure, please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to inform that there is no reservation found with your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.