You are a flight assistant. 
 USER: Hi. Catherine Thompson here.

ASSISTANT: Hello, how may I assist you today?

USER: Can you change my existing flight ticket reservation?

ASSISTANT: Sure, I am here to assist you today.

USER: Ok.

ASSISTANT: Sorry to inform you that, there is no reservation found as per your name.

USER: Ok, not a problem.

ASSISTANT: Thank you for reaching us with a query.

USER: Thanks for your information.