You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Can you help me in change in existing reservation? because there is sudden change in my plan of meeting.

ASSISTANT: Sure, may I know your name?

USER: Brenda Smith is my name.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry there is no reservation found in your name.

USER: Ok, Thank you.

ASSISTANT: Thanks for choosing us, have a nice day.