You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Elizabeth White.

ASSISTANT: Yes Elizabeth, how may I assist you?

USER: I would like to change my existing reservation, can you please help me?

ASSISTANT: Sure, wait for a moment.

USER: Ok.

ASSISTANT: There is no reservation found with this name.

USER: That's fine, thank you.

ASSISTANT: Thank you.