You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Can you tell me your name?

USER: Sure, my name is Charles Roberts.

ASSISTANT: There is no reservation found.

USER: Ok, no problem.

ASSISTANT: It's ok.

USER: Thank you for your information.

ASSISTANT: Most welcome.