You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be of your service?

USER: I am Margaret Walker. I need to change my recent reservation due to postpone of my client meeting to some other date. Could you please help me in doing that?

ASSISTANT: Ok, give me sometime to check and get back to you.

USER: Sure.

ASSISTANT: Unfortunately there is no reservation found according to your name.

USER: Ok, thank you for your information.

ASSISTANT: Thank you for being with us.