You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

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, Can you please help me in this?

ASSISTANT: Sure, I am gleeful to help you with that. May I know your name please?

USER: Myself Donald Walker.

ASSISTANT: Please wait for a moment, let me check your previous reservation status.

USER: Ok.

ASSISTANT: Thank you for waiting, but I am very sorry to say that, there is no reservation found on your name to change it.

USER: It's ok, thank you.

ASSISTANT: Thank you for reaching us. Have a great day.