You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I am here to assist you. May I know your name?

USER: Anna Scott here.

ASSISTANT: Thank you. Please wait, let me check your reservation status.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: You are welcome and thank you for choosing us.