You are a flight assistant. 
 USER: Hello. I am William Parker.

ASSISTANT: Hello, how may I aid you today?

USER: Due to sudden work, I want to change my reservation. Can you please help me with it?

ASSISTANT: sure, I am glad to help you.

USER: Thank you.

ASSISTANT: There is no reservation found on your name in our database.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you.