You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you?

USER: I am Ronald Hill. As my joining date got rescheduled, I want to change my existing reservation. Can you please help me?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.