You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: Can you help me in changing the travelling dates of my existing reservation?

ASSISTANT: Sure, I will assist you with that. Could you please mention your name for checking your previous reservation status?

USER: I am Katherine Lee.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: There is no previous reservation available under your name.

USER: Its ok, thank you.

ASSISTANT: Thank you for reaching us.