DMC debt Management overcharging people

I have a problem with this company DMC Debt Management. I was handed over by Foschini In 2020 to this company with the amount of R2500.00 and since i have been blacklisted. Now i want to pay my debt Foschini referred me to DMC Debt Management because they said they can not fine my account. I spoke to the debtors clerk and they informed me that my debt is R11, 556.10 how is that possible. One of the agents informed me that the account might be prescribed and would inform me more about it but never did and told me that if I want to settle must pay R6600. I then asked for my statement, their interest and also their breakdown costs to see how they calculated to reach R11,556.10 .The agent provided me with a letter that tells me to pay the R6600 not the information I requested, when I insisted on it and told them it is within my right to get what I requested they told me to go to Foschini and then that was it