You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be at your service today?

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: May I know your name please to check the status of your reservation?

USER: I am David Thomas.

ASSISTANT: Thank you. Please stay online for a while, I will check your reservation status and let you know.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

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

ASSISTANT: Thank you for reaching us.