You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I would like to change my reservation, as my holiday trip has been postponed. Can you please help me with that?

ASSISTANT: Sure, I can help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Sure, my name is Frank Collins.

ASSISTANT: Give me  a minute.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for choosing us.