You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Robert Davis. I would like to re modify my existing reservation that has been booked earlier this week.

ASSISTANT: Sure Robert, please give me minute to check.

USER: Sure, please take your time.

ASSISTANT: Apologies Robert, there is no reservation available on your name.

USER: Ok. Thank you for the information.

ASSISTANT: You are most welcome.