You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Could you please help me to change my existing reservation due to postpone of my client meeting?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please to proceed for further process?

USER: My name is Joseph Baker.

ASSISTANT: Joseph Baker, sorry to inform you that no reservation found in our database.

USER: Ok, not a problem. Thank you for the information.

ASSISTANT: Thank you.