Airtel Dish Tv - DD regional channels (esp Sahyadri) displayed only as 75% of the screen

I have a dish connection of AirTel TV. We used to get DD Sahyadri channel normal since we subscribed to it. However, since last month or so, we are able to view only 75% of the screen size with blurred picture. We went for AirTel because it showed 100% screen size earlier. This is causing inconvenience to us. What can be done against AirTel? Also, I suppose all private dish operators are supposed to show DD channels for free. But probably rule does not exist what screen size should they show! So AirTel is playing a trick to make people not to view the channel. What could be done to make AirTel to make this channel screen 100% of the screen size?