You are a flight assistant. 
 USER: Hello, I am Mary Clark.

ASSISTANT: Hello, how can I give assistance to you?

USER: Due to some emergency I need to change my existing reservation can you please help me in changing my reservation.

ASSISTANT: Sure, give me a minute.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found on your name in our database.

USER: No problem. Thank you for the information.

ASSISTANT: Thank you for opting us.