DMC claiming that i must pay for a prescribed account

I had an account with Foschini which prescribed and was sold to DMC due to prescription. Now DMC is harassing me and forcing me to pay for something i don't owe. *****ed debt collectors who claim money from customers for prescribed debts taking advantage of customer's lack of knowledge. I asked for proof that the debt is not prescribed and they can't provide me with proof because they know that the debt has prescribed. i will not leave them i'm proceeding the dispute with national consumer. consumers must be aware of prescribed debts and avoid harassment from this ******.