You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. May I know how best I can help you today?

USER: Due to some urgent entrepreneurship meeting, I am willing to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, I'll try to change an existing reservation.

USER: Thank you.

ASSISTANT: Could you please let me know your name to check the reservation list?

USER: Debra Johnson.

ASSISTANT: Thank you for sharing your name, please wait a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry to to inform you that there is no reservation found by this name.

USER: No issue. Thank you.

ASSISTANT: Thank you for availing us.