HARRASSMENT BY MBD AND EXCESSIVE INTEREST/COSTS

I have been paying off an account for more than 6 years with MBD who bought my ABSA Credit Card. The original debt was R10,158.90. I have paid R6590.00 to date, as that was all I could afford being a single mother of 2 children, with no maintenance received from their father. I requested a statement recently and were told that the balance is now R13,727.80. How can I owe more now than 6 years ago. They also chase up the fees/costs by phoning and sending SMS's sometimes 3 times per day, on multiple days of the month. That is total harassment. They some times phone you on 07h00 on a Saturday when you are still sleeping. How can that be legal? I have told them on numerous occasions I will not pay a cent more until they fix my outstanding balance. This debt has actually prescribed as it is more than 10 years old as well. The consultants that phone you are extremely rude and ***********. I am also sure that they have missed some of my payments, but will be speaking to ABSA directly today.