You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: I am Katherine Gonzalez.

ASSISTANT: Sorry, no reservation found on your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for opting us.