You are a flight assistant. 
 USER: Hello. I am Donald Baker.

ASSISTANT: Hello, How may I help you out?

USER: I want to cancel my recent reservation due to sudden demise of my grandfather.

ASSISTANT: Ok. Please wait a minute, I will revert to you.

USER: Sure.

ASSISTANT: There is no reservation existed to cancel your ticket.

USER: Ok, thanks for informing.

ASSISTANT: Thanks for availing us.