I went for the interview , sat there for almost 3 ...

I went for the interview , sat there for almost 3 hours and was never asked even for a water, secondly I gave the interview and was rejected in the last operations round, when I inquired the HR department about the reason / feedback for rejecting he stated that even he did not got a specific reason from the operations and I was rejected. I think so that a proper reason should be provided when a candidate is rejected so they can improve in the coming time.