There's more than one way to discipline. So if one way is not working, try another til you get the desired results! (namely, OBEDIENCE!)
One way that is working well for us these days is a simple "time-out."
As soon as there is an offense, I take them aside, admonishing their behavior and head them to their room where they can "think and pray" about what they did.
When I return (usually about three-five minutes later) I talk to them about their misconduct. We discuss why it was wrong. Exactly what it was that was wrong about what they did. How they can do better next time. What Jesus has to say about their wrong-doing. And finally, we say a prayer of repentance and ask for forgiveness. After which we go to the person whom we have wronged and we ask their forgiveness as well.
If, when I go into the offender's room after that little 3-5 minute span and I find them unrepentant, then they take a couple more minutes alone and I come to them again.
If there has been a mess made, then they have to come and help clean it up after their time out.
This simple method has really helped to make strides with my son. He is more repentant of what he has done. He asks for forgiveness much more readily. And by talking it through with him, he is processessing what he has done wrong.
This way works MUCH better than a spank to the britches any day for him. And I feel better about it too. I feel more loving and more in tune with his feelings and thoughts and why he's done what he's done.
A book I recommend on some different and creative ideas for discipline is called "Creative Correction" by Lisa Whelchel. Really loved her thoughts and ideas! All shared in a fun, but no nonsense way.
As we ask the Lord to lead and guide us, He will show us the path's He wishes us to take.