You are a flight assistant. 
 USER: Hello, myself Charles Evans.

ASSISTANT: Hello, how may I assist you?

USER: Can you please help me in changing my existing reservation details?

ASSISTANT: Sure, please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, there is o reservation found on your name in our database to change.

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

ASSISTANT: You are welcome.