By definition, challenging behavior is difficult to solve. If it were easy, the simple consequences should have worked. The reason nothing has worked is because the underlying cause of the problem is not being addressed. The trick is figuring out the root cause of the problem behavior.
Forcing Children to Behave
While it is tempting to try to force children to behave through the use of punishments or rewards, these attempts often fail. Children realize that you are trying to control their behavior and may respond by doing just the opposite of what you'd like.
Dr. Ross Greene talks about three approaches to misbehavior in his book The Explosive Child. "Plan A" involves trying to impose your will on the child.
He writes "If you respond to an unsolved problem by imposing your will - by saying things like 'No,' 'You must,' or 'You can't' - you're using Plan A. If your child often has trouble completing homework and you respond by insisting that the homework be completed, you're using Plan A. If your child often doesn't brush his teeth with the frequency or diligence you expect and you take away screen time until your expectation is met, you're using Plan A."
(read the rest of the article at Priceless Parenting)