You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Gregory Campbell.

ASSISTANT: How can I help you today?

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

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you.

ASSISTANT: Sorry, no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us, have a nice day.