You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Joshua Phillips. I have to do some modification in my previous flight ticket booking that there is a sudden event held at my home town, so I am unable to travel the trip. can you please help me out with changing of my reservation?

ASSISTANT: Please wait a while.

USER: Thank you. Sure.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.