When will they learn!????

....that when they fight and argue they get less not more.....For the third day in a row Mark and Chloe are sitting in time out....still arguing and fighting and blaming each other rather than taking responsibility for their part in the disagreement. The noise level in our house right now is deafening even to my partially deaf ears and even a call to dad did not put an immediate end to the bickering....so now they sit in time out. What privilege can I take away now that they have already lost so many. What can I do to help them get along?