You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I need to change my reservation as my exams got postponed. will you please change my trip dates of my existing reservation?

ASSISTANT: Can I know your name?

USER: I am Jack Smith.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting and sorry there is no active reservation found on your name to change.

USER: Ok fine, thanks for your response.