You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am William White.

ASSISTANT: How can I assist you now?

USER: In my previous reservation, I gave wrong airport codes so can you help me for changing my existing reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Sorry William, there is no reservation found on your name.

USER: Oh! It's ok, no problem.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: You are welcome.