You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Due to some problems in my business, I would like to change my existing reservation.

ASSISTANT: Sure, could you please specify your name?

USER: Sure, my name is Mary Hall.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry Mary, there is no reservation found on your name to change your reservation.

USER: Ok, thank you for your information.

ASSISTANT: Do you want any other help from me?

USER: No, thank you.

ASSISTANT: You are welcome.