You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you now?

USER: I am Frank White, can you help me for changing my existing reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

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

USER: Oh! It's ok, no problem, thank you for your services.

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