You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Due to sudden work, I want to change my reservation. Can you please help me with it?

ASSISTANT: Sure, may I know your name please?

USER: Karen Williams here.

ASSISTANT: I am sorry no reservation found on your name.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for choosing us.