You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my existing reservation. Can you help me in that?

ASSISTANT: Sure, I am mirthful to help you with that. May I know your name please?

USER: Myself Michael Campbell.

ASSISTANT: Please wait for a while, let me check your previous reservation status.

USER: Ok.

ASSISTANT: Thank you for waiting. There is no active reservation found on your name in our reservation list to change it.

USER: Ok, no problem. Thank you.

ASSISTANT: Most welcome, thank you for choosing our agency. Have a great day.