You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I assist you?

USER: I want to change my existing reservation, so can you help me with that?

ASSISTANT: OK, may I know your good name please?

USER: Yes, you can call me as Nancy Taylor.

ASSISTANT: OK, Please wait for some time I will check and get back to you.

USER: OK.

ASSISTANT: Thank you for waiting. There is no reservation found based on your name.

USER: OK, thank you for your information.

ASSISTANT: Thank you. Have a nice day.