You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you today?

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

ASSISTANT: Can you provide me your name please?

USER: Sure, my name is Donald Collins.

ASSISTANT: Sorry, no reservation found under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: You are welcome.