My tata indigo overheating problem

My tata indica dlx turbo 2007 model, I work my car in engine gasket but not solve my problem. My car radiator fan is properly on but no properly off. I change temperature switch, thermostat, gasket, radiator cleaned but not my problem solve.

I have seen other vehicles also changed the radiator. There is no point on, the engine may be a problem. I've also changed the gasket in the car, cleaned Radiator, see also changed the second Radiator, has also changed, but in vain, Temperature switch changed.

Piston what the problem might be, say, my mechanics have seen it all now, once Piston also take Check that might be out there Piston.

please help me