You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I render you today?

USER: I am Daniel Smith.

ASSISTANT: Ok.

USER: I want to change my existing reservation due to postpone of my client meeting, can you help me in change reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry to say that, there is no reservation found on your name in our data base.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for reaching us.