You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Due to sudden work at my office, I want to change my existing reservation. Can you please change my existing reservation?

ASSISTANT: Ok, I am here to help you with that. May I know your good name?

USER: I am Michael Lee.

ASSISTANT: Ok, wait for a minute.

USER: Ok.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database.

USER: Ok, Thank you for your help.

ASSISTANT: Thank you for reaching us.