You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Can you please change my existing reservation?

ASSISTANT: Sure. Could you please provide me your name please?

USER: I have booked my flight ticket from Denver, but my exams have postponed so I have to change my existing reservation. Myself Laura Phillips.

ASSISTANT: Laura, there are no active reservations found with your details.

USER: Ok, that's fine.

ASSISTANT: Thank you for choosing our services.

USER: Thank you for your help.