You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Gregory Brown here.

ASSISTANT: How may I assist you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, I am here to help you out.

USER: Ok.

ASSISTANT: Gregory Brown, we haven't found any reservation under your name in our database.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for reaching us.