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

ASSISTANT: Hello King, how may I help you today?

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

ASSISTANT: Sure, I am here to help you. Sorry to say , that there is no reservation found as per your name to change it in your database.

USER: Ok, not an issue. Thank you.

ASSISTANT: You are welcome.