Mantaray,
i think withholding a toy or toys, or restricting tv for one or two days may work very well. I used this as a very effective parenting tool when needed in the past. I'd even heard the kids whispering when they thought i was asleep(when we get up in the morning we can watch tv on mute and mum will never know)little did they know that i had pulled it out of the wall. it stayed that way for two days,and something even i discovered its much more fun to play cards or monoploy then watch telly....