You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Michael Gonzalez.

ASSISTANT: Michael, how can I assist you?

USER: My plan to visit Houston is suddenly changed, so I want to change my reservation. Can you please help me?

ASSISTANT: Sure. Sorry, no reservation found by your name.

USER: That's ok.

ASSISTANT: Thank you for contacting us.