You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Kenneth Perez.

ASSISTANT: How can I help you?

USER: I want to change my existing reservation, can you help me in changing the reservation please?

ASSISTANT: Sure. Please be on hold, I will check and revert back to you.

USER: Ok, take your time.

ASSISTANT: Sorry Kenneth, there is no reservation found  on your name in our data base. Thank you for approaching us, have a nice day.

USER: Ok no problem, thank you for your information.

ASSISTANT: Welcome.

USER: Have a great day.