You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Catherine harris.

ASSISTANT: How may I assist you?

USER: I need to change my existing reservation, can you please help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

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

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.