You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be your help today?

USER: I made my reservation in advance, but now I don't have any leaves so want to change my reservation.Please help me to change it.

ASSISTANT: Sure, I am here to help you.

USER: Thanks for considering my request.

ASSISTANT: May I know your name to look for your current reservation?

USER: Sure, my name is Margaret Campbell.

ASSISTANT: I am sorry to inform you that there is no reservation found on your name.

USER: Ok, no worries. Thank you.

ASSISTANT: Thank you.