You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I want to change my existing reservation due to prepone of my exams. Can you help me in that?

ASSISTANT: Sure, I am here to help you out. Please provide me your name.

USER: Myself William Thompson.

ASSISTANT: Sorry  William Thompson, there is no reservation on your name.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for reaching us.