You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Karen Jackson. I want to change my existing reservation due to bad weather condition, can you please help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Sorry Karen, there is no reservation found as per your name to change it.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome.