I dont get it, i have been in credit card debt for 6 years but its the same balance & no intrest, why?

I mean the letters i keep getting show the same balace of my credit card debt, i though intrest is charged if you dont pay up? i have not gotten back to the collectors, agencies, creditors etc, but the warning letters i get or whatver show the same balance, does default mean the balance is same & not be charged for intrest?
Answer
You just wait till they catch up with you - and boy, are you in for a surprise ! ! !