You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you at present?

USER: I am Betty Brown. I want to change my existing reservation. Could you help me?

ASSISTANT: Sure, we are here to help you to change it. Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there was no reservation found on your name.

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

ASSISTANT: Thank you for reaching our service.