You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I support you?

USER: I want to change my existing reservation. Can you please help me in this?

ASSISTANT: Sure, may I know your name please?

USER: I am Karen Johnson.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry, we do not found any active reservation with your name.

USER: Not a problem, thank you.

ASSISTANT: Thanks for approaching us.