You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Donald Mitchell.

ASSISTANT: How may I aid you at this moment?

USER: I want to change my reservation which I have booked last week as my schedule got postponed. Can you please help me about that?

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you for considering my request.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database.

USER: It's ok, it might not be done properly at the time of booking. Anyway thank you for the information.

ASSISTANT: Thank you for consulting us.