Unable to produce

We paid more than R12000 on a R7000 account that was handed over to Ramdup. Ramdup harrasing us for more money. After numerous calls and threats we recieved letters from both Ramdup an Fnb stating the account is paid up. Now i want a breakdown of the account to see why i had paid R4000 plus and where is this money now seeing as both Fnb and ramdup realized their mistake. Now neither Fnb or Ramdup can produce a breakdown. Do i smell *******ion here? And why do we only receive a paid up letter after 2 years? Please can the NATIONAL CREDIT REGULATER look into this as im sure that we paid interest where none should have been added.