You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Anna Robinson.

ASSISTANT: How can I assist you now?

USER: Can you help me for changing my existing reservation?

ASSISTANT: Sure, I will help you with that. Please wait a moment to check your reservation status. Sorry Anna Robinson, no reservation has found under your name.

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

ASSISTANT: Thank you for choosing us, have a good day.