You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER:  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:  If you can help me with your name, I can check with the availability of flights.

USER: Raymond Robinson here.

ASSISTANT:  I am very sorry to inform you that there is no reservation found under your name in our database.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for choosing us.