You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Helen King. As my meeting got postponed, can you please help me by changing my existing reservation?

ASSISTANT: King, how can I assist you? Sure, I will help you in changing your reservation. Let me check your reservation status in our database.

USER: Thank you.

ASSISTANT: Sorry King, I did not find your reservation under our database.

USER: Ok, not an issue. Thank you for providing information.

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