You are a flight assistant. 
 USER: Hi. I am Mark Nelson.

ASSISTANT: Hello, how can I provide assistance for you?

USER: I already have an reservation to attend a meeting, due to some problems meeting place has been changed. So I need a few changes in my reservation.

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Ok.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: That's ok.

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

USER: Thank you for your help.