You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation due to postponed of my exam dates. Can you please help me with this?

ASSISTANT: Ok, please can I know your name please?

USER: My name is Karen Lee.

ASSISTANT: Ok, please wait a moment I will check.

USER: Sure.

ASSISTANT: Ok, thank you for waiting. Sorry, there is no reservation been fund on your name to change.

USER: No problem, thanks for your information.

ASSISTANT: Ok, thank you for choosing our agency.