You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: My holiday vacation has been postponed, can you please help me for changing the existing reservation?

ASSISTANT: Sure, I will help you help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Charles Roberts.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thank you for your information.