You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: My name is Robert Garcia.

ASSISTANT: Yes Garcia.

USER: Actually I have a seminar to present in Las Vegas,  but due to some problems, the location of seminar is changed to Chicago ORD. Could you help me in changing the existing reservation?

ASSISTANT: ok. Sorry there is no reservation found for you to change.

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you for choosing us.