You are a flight assistant. 
 USER: Hello. I am Dorothy Anderson.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation as my tour got postponed, please help me out.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry to say that, there was no reservation found with your name.

USER: That's fine, thank you for the information.

ASSISTANT: Thank you for choosing us.