You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Robert Robinson.

ASSISTANT: How can I help you?

USER: My plan to visit Atlanta is postponed as of now so, I want to change my existing reservation.

ASSISTANT: Sure. Give me a moment.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome.