You are a flight assistant. 
 USER: Hello, I am Thomas Lee.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation,due to my interview has been postponed. Can you help me to change it?

ASSISTANT: Sure, please wait for a while. Thanks for waiting, no flight reservation found with your name.

USER: Ok, thanks for your help.

ASSISTANT: Thank you for choosing us.