You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Deborah Mitchell here. I am fallen sick due to which I would like to change my recent reservation.

ASSISTANT: Sure, I will help you out.

USER: Ok.

ASSISTANT: Sorry Deborah, no reservation has been found on your name in our database.

USER: That's not a problem. Thank you for your service.

ASSISTANT: Thank you for choosing our service.