You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I would like to change my flight reservation as my trip got postponed, can you please help me?

ASSISTANT: Sure, I will help you with that. May I know your name please?

USER: I am Rebecca Collins.

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

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.