You are a flight assistant. 
 USER: Hello. I am Jack Walker.

ASSISTANT: Hello, how may I aid you?

USER: Please help me to change my reservation as my meeting was postponed.

ASSISTANT: Sure, I can help you. Please wait for a moment.

USER: Ok, I will wait for your response.

ASSISTANT: Thanks for your time, there is no reservation found in your name to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.