You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I would like to cancel my reservation because already my friend has reserved a seat in UA airline I don't that he booked it.So, can you help me in cancelling the reservation?

ASSISTANT: Sure, I will help you. May I know your name please?

USER: Please, check the previous reservation details on Sarah Taylor.

ASSISTANT: Ok, Please wait, I will check the status and notify you.

USER: Ok, fine.

ASSISTANT: Thank you for waiting, we are sorry to tell you that no reservation has found based on your name.

USER: That's ok, I think my reservation has not done properly while booking that the reason my reservation details are not found in your data base.

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

USER: Thank you for your information.