You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist 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: Sure, may I know your name?

USER: I am Helen Walker.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for opting us.