You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Frank Wilson. I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: No issue. Thank you.

ASSISTANT: You are welcome.