You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I need to change my existing reservation due to urgent meeting, can you help me?

ASSISTANT: Sure, I am here to help you out. May I know your name please?

USER: I am Linda Clark.

ASSISTANT: We regret to inform you that, we haven't found any reservation under your name in our database.

USER: That's ok. Thank you for your service.

ASSISTANT: Thank you for choosing us.