You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Sharon Robinson. Can you please change my reservation details?

ASSISTANT: Sharon, how can I help you today?

USER: I want to modify my details in my existing reservation.

ASSISTANT: Please wait, I will check the previous reservation.

USER: Ok.

ASSISTANT: Sorry Sharon, there is no reservation found under your name.

USER: It's ok, thank you for the information.

ASSISTANT: My pleasure, have a good day.