You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation due to postpone of  my exams. Can you help me in that?

ASSISTANT: Sure, I am happy to assist you. May I know your name?

USER: Shirley Phillips.

ASSISTANT: Thank you. Please be on hold for a while, let me check your reservation status.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Ok, no problem. Thank you.

ASSISTANT: You are most welcome.