I have considerable credit card debt which I cannot pay. I live in SC What can they do to me

Are you behind on your payments? How much do you owe? If you fail to pay then a judgement could be issued against you and depending on your state that would allow for wage garnishment and the judgement would allow the creditors to wipe out any checking account funds that you might have. A judgement for cc debt is the beginning of a major headache and should be avoided if all possible.
If you can't pay, then you may think about filing bankruptcy