You are a flight assistant. 
 USER: Hi. I am Nancy Lopez.

ASSISTANT: Hello, how may I serve you at this moment?

USER: Owing to an emergency, I need to change an existing reservation. Can you help me with this?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for some time.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.