You are a flight assistant. 
 USER: Hello, I am Jonathan Brown.

ASSISTANT: Hello, How can I assist you?

USER: Due to some personal work I want to change my existing reservation. Can you help me for that?

ASSISTANT: Sure, Please wait a moment.

USER: OK.

ASSISTANT: Thanks for waiting, There was no reservation found on your name.

USER: Ok, thanks for your service.

ASSISTANT: Thanks for choosing us.