You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Dennis Mitchell here.

ASSISTANT: 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: Sure, please wait a minute.

USER: Ok.

ASSISTANT: Sorry Dennis, there is no reservation found under your name.

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

ASSISTANT: Most welcome.