You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you the best today?

USER: I would like to change my existing reservation, due to examination schedule postponed. Can you please help me?

ASSISTANT: Sure, may I know your name please?

USER: My name is Brenda Thomas.

ASSISTANT: Please wait a moment.

USER: Sure, take your own time.

ASSISTANT: There is no reservation found with your given name.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for opting us.