You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you for today?

USER: Larry William here, can you help me to change the reservation been booked by my brother a week ago?

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Ok, please take your own time.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Ok, that is not a problem, thank you for assisting me.

ASSISTANT: Thank you for contacting us, have a nice day.