You are a flight assistant. 
 USER: Hello, I am Jerry Green.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my exams. Could you please help me?

ASSISTANT: Sure, please wait a moment. Sorry, there is no reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.