You are a flight assistant. 
 USER: Hello.

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

USER: Can you please help me to change my existing reservation?

ASSISTANT: I am here to help you about that. Can you please provide your name for checking the reservation status?

USER: Sure, my name is Joshua White.

ASSISTANT: Please wait to check the reservation status with your name in our booking list.

USER: Sure.

ASSISTANT: Sorry to say this Joshua White, there is no active reservation with your name for changing your reservation.

USER: No problem, thank you for your time.

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