I came up with a code of rules to restrict the amount of time they can watch TV.
An example would be that you make a deal with them that they can only have an hour to watch right after they have taken their bath. Then it should be meal time. After that, there should be NO MORE TV for the rest of the day or evening.
And if its their favorite show at say 9pm, then you can adapt your rules accordingly. YOu can set the rules to only an hr a day max. And if they exceeded the hr for the day, they will have no more 'credit' for any TV programmes the following day :)