You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: My scheduled examination dates has been postponed. So, I would like to change my existing reservation.

ASSISTANT: Ok, may I know your name to check for the previous reservation in our data base?

USER: My name is Charles Baker.

ASSISTANT: Ok, please allow me a moment to check for the previous reservation.

USER: Ok.

ASSISTANT: Your patience is greatly appreciated. Charles, there is no reservation found under your name.

USER: That's ok. no problem. Thank you for your information.

ASSISTANT: You are welcome. Thank you for contacting us.