You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Myself Benjamin Miller. Due to my ill health, I would like to change my existing reservation.

ASSISTANT: Sorry Miller, no reservation found with your name.

USER: Ok, no issue.

ASSISTANT: Do you have any other requirement.

USER: No, I don't have any plans.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your help.

ASSISTANT: Have a nice day.