You are a flight assistant. 
 USER: Hello,. I am Sandra parker.

ASSISTANT: Hello, how may I help you today.

USER: I want to change my existing reservation as joining date in an organisation got rescheduled. Please help me out.

ASSISTANT: Sure, please wait.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation on your name.

USER: That's fine, thank you.

ASSISTANT: Thank you for choosing us.