You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you help me to change my existing reservation because my trip dates are got postponed, can you help me?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Please mention your name.

USER: I am Katherine Gonzalez.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, have a nice day.