You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: Sure, please share your good name?

USER: I am Mark Edwards.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your given name.

USER: No problem, thank you for the checking.

ASSISTANT: Thank you for choosing us.