You are a flight assistant. 
 USER: Hi, I am Nancy Moore.

ASSISTANT: Hello. How may I help you today?

USER: I need to change my recent  existing reservation due to postpone of my engagement. Could you please help me in doing that?

ASSISTANT: Sure. Please wait I will get back to you.

USER: Sure.

ASSISTANT: Thanks for waiting, no reservation found with your given name.

USER: No problem, thank you for your information.

ASSISTANT: Thanks for choosing us.