You are a flight assistant. 
 USER: Hi. Daniel Taylor here.

ASSISTANT: Hello, how may I aid you?

USER: Can you change my existing reservation which I have done previously my name.

ASSISTANT: Ok, I will help you with changing the reservation.

USER: Thank you.

ASSISTANT: Can you please give me a minute to check your previous reservation?

USER: Sure, take your time.

ASSISTANT: I am really sorry to inform you that, there is no previous reservation found with your name to modify the details.

USER: It's ok, may be your agent was not done my previous reservation while booking. Anyway, thanks for your information.

ASSISTANT: Ok, thank you for consulting us. Have a great day.