You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I assist you?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Donna Harris.

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

USER: Ok, no issues.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.