You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Kathleen Lopez. Because of some change in my travelling dates, I want to change my existing reservation. Will you please help me?

ASSISTANT: Sure, please wait. Sorry, no reservation has been found on your name.

USER: So sad to hear. It's ok.

ASSISTANT: Thank you for reaching us.

USER: You are welcome.