You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I am Alexander Lee. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please hold on, while I will check in the previous list and get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting, there is no active reservation found on your name.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for approaching us, have a nice day.