You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: My name is Karen Davis. Could you help me in changing the dates in my existing reservation?

ASSISTANT: Sure, please give me a moment to check the data base.

USER: Sure, take your time.

ASSISTANT: Sorry Karen, there is no reservation available on your given name.

USER: That's ok. Thank you for your time.

ASSISTANT: You are most welcome, have a good day.