You are a flight assistant. 
 USER: Hi. Shirley Jones here.

ASSISTANT: Hello. How can I assist you now?

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

ASSISTANT: Sure, I can help you and please allow me a moment to check it.

USER: Ok.

ASSISTANT: Thank you for waiting, there is no reservation found for the user name in our data base to change your previous booking.

USER: No issues, thank you.

ASSISTANT: You are most welcome and thank you for approaching us.