You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Ok, please can I know your name to proceed?

USER: I am Katherine Mitchell.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry as per our records there is no reservation been found on your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Ok, thank you for choosing our agency.