You are a flight assistant. 
 USER: Hello.

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

USER: I want to change my existing reservation as my plan to visit Washington trip has been postponed. Can you help me with that?

ASSISTANT: I am here to help you about that. Can you please provide your name to check the booking list?

USER: Thank you. I am Melissa Collins.

ASSISTANT: I regret to say this Melissa Collins, there is no active reservation with your name to change the reservation.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: You are welcome, thank you for reaching us.