You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi. How can I help you?

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

ASSISTANT: Sure, may I know your name please?

USER: Sure, I am Kathleen Clark.

ASSISTANT: I am sorry no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you for checking.