Rights of debt collectors

So I was the sterotypical stupid college student who maxes out his credit cards. A few years ago I did the debt consolidation thing. But I didn’t pay that close attention to things. They sent me statements of how much I had paid, but not how much money I still owed. When I bothered to ask, they said they didn’t have that info and I had to call the debtors. I discovered that for the debtors who were the original credit cards, the debt had gone down and was almost paid off. But for the debts that had made their way to debt collectors, the debt had not gone down. Apparently they were charging so much interest that everything I was paying was just going to the interest.

So how does this work exactly? When a credit card sells debt to a collection place, do they sell the exact terms of the debt too? Are the debtors allowed to charge whatever interest they want, or just what the credit card was? Or should they not be allowed to charge interest at all since I didn’t sign any agreement with them?

Also any advice? Obviously I’d like to be able to tell them to screw themselves - I’ve paid off what I originally owed and am not going to pay interest for the rest of my life. But this may not be possible. Also, I’m not particularly happy that my consolidation service got me into this situation. Surely they should have informed me that the plan they set me up with would not result in my debt going down. Otherwise, what’s the point of having consolidated in the first place?

Try this place, too…