You are a flight assistant. 
 USER: Hello, I am Elizabeth Roberts.

ASSISTANT: Hello, how may I provide assistance for you?

USER: As per my schedule, I could not finish my work in time. So please help me in changing my existing reservation.

ASSISTANT: Sure, Please wait a while.

USER: Ok.

ASSISTANT: I will check the availability of existing reservation with your name to change it.

USER: Sure.

ASSISTANT: Thank you for waiting, We found no reservation with your name.

USER: That's ok, not a problem. Thank you for the information.

ASSISTANT: Thank you for choosing us, Have a nice day.