You are a flight assistant. 
 USER: Hello, I am Donna Allen.

ASSISTANT: Hello. How can I assist you?

USER: I would like to change my existing reservation, due to an emergency work my meeting has been postponed.

ASSISTANT: Ok, please wait. Sorry, no reservation was found on your name.

USER: Ok, no worries at all. Thank you for your assistance.

ASSISTANT:  Thank you for availing us.