You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to change my existing reservation, can you help me in that?

ASSISTANT: Sure, I will help you. Please help me with your name.

USER: Sure, myself Dorothy Collins.

ASSISTANT: Please allow me a minute.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you. I am really sorry to inform you that there is no booking done on your name to make changes as per your request.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us. Have a great time.