You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you at this moment?

USER: Can you please help me to change my existing reservation, due to my exams has been postponed?

ASSISTANT: May I know your good name?

USER: Sure, my name is John Hernandez.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: There is no reservation found on your given name.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us.