You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: I am Katherine  Williams. I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I will help you out in this. Please standby.

USER: Sure.

ASSISTANT: Thank you for your time. Sorry, no reservation found with your given name in the data.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for availing with us. Have a nice day.