You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brian Roberts.

ASSISTANT:  How can I aid you?

USER: I need to change my existing reservation, my planned to visit has been postponed.

ASSISTANT:  Ok, please wait I will revert you.

USER: Sure.

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

USER: Ok, no issues at all. Thank you for your service.

ASSISTANT:  Thank you for reaching us.