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

ASSISTANT: Hello. How can I assist you?

USER: Owing to an emergency, I want to change an existing reservation. Could you help me in changing the reservation?

ASSISTANT: Ok, please wait I will revert you.

USER: Sure.

ASSISTANT: Sorry, no reservation was found on your name in our data base.

USER: Not an issue. Thank you.

ASSISTANT:  Thank you for availing us.