You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be your helping hand today?

USER: I would like to change my recent reservation because my trip dates are postponed, can you help me?

ASSISTANT: Sure, we are glad to help you to change it. On whose name, your reservation has been done earlier?

USER: I am Jonathan Nelson.

ASSISTANT: Please wait for a while, I will check with your previous reservation list and revert to you.

USER: Sure, take your own time.

ASSISTANT: Sorry to inform you that, we did not find any reservation on your specified name to change it.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching our service.