You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Yes, can you tell me your name?

USER: Donald Clark.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for reaching us.