You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you today?

USER: Please help me to modify my existing reservation.

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

USER: Thank you.

ASSISTANT: Can I know your good name?

USER: Gregory Martinez here.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for approaching us.