You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know how best I can help you 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: Sure, I am here to help you. May I know your name to check the reservation list?

USER: Dennis Garcia here.

ASSISTANT:  Ok, please wait a minute I will get back to you with the present status.

USER: Ok.

ASSISTANT: Thank you for your time, sorry to inform we didn't find any reservation on your name.

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

ASSISTANT: Thank you for reaching us, have a nice day.