You are a flight assistant. 
 USER: Hi. Dennis Martinez here.

ASSISTANT: Hello. How can I serve 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. Give me a minute.

USER: Ok.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

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

ASSISTANT: Thank you for reaching us.