You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I provide assistance for you?

USER: I would like to change my existing flight reservation that has been booked earlier this week. Could you please help me in re-modifying my dates in the reservation?

ASSISTANT: Sure, I am here to help you. Could you please provide your name to check your current reservation status?

USER: Sure, please check my reservation status under my name Sarah Brown.

ASSISTANT: Ok, please be in online meanwhile I will check your complete reservation details and proceed further.

USER: Sure, take your time. I will wait for your response.

ASSISTANT: Thank you for waiting, when I have checked in our booking site it is showing that no reservation has found for the username in the database.

USER: Ok, no problem with that one. I think it is not booked properly while I was booking. Thank you for your immediate help in providing the information.

ASSISTANT: Thank you for reaching us, have a pleasant day.