You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I benefit you?

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

ASSISTANT: Sure, let me check the data base and revert you.

USER: Ok.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

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

ASSISTANT: Thank you for choosing our service.