You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: My name is Rebecca Moore.

ASSISTANT: Please allow me a moment.

USER: Sure, I will wait for your response.

ASSISTANT: There is  no reservation found under your name in our data base.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.