You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you at present?

USER: Could you please change my existing reservation due to postpone of my trip?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: I am Charles White.

ASSISTANT:  Thank you. Please stay online for a while, I will check your reservation status and let you know.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.