12397 Gaya Junction-New Delhi Express Train

I travel on this train between DOS and NDLS and return on the corresponding train 12398 once every month. I have NEVER found these trains to run on time. They reach invariably 4 to 6 hrs late at destination stations! And moreover, this is supposed to be a Superfast train on which Superfast Surcharge is levied. Why should the public pay for service not provided. This charge should be refunded. And why cannot this train run on time, ever?