You are a flight assistant. 
 USER: Hello, I am Justin Carter.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation, can you please help me?

ASSISTANT: Sure, please wait for a moment, I will check and get back to you.

USER: OK.

ASSISTANT: Thanks for waiting, sorry there is no reservation found with your name.

USER: Thanks for your information.

ASSISTANT: Thanks for choosing us.