Can't close account after settlement with attorneys

I had a personal acc with FNB. With an overdraft of R7000. They stopped my account and handed me over to attorneys. So, I started paying a monthly installment to the attorneys. They offered me a special settlement amount (lower than the outstanding balance) and I accepted. I paid the amount, got the settlement letter, tried getting FNB to permanently close the account and nearly 1 year later.... nobody at FNB or their attorneys could help me correct the balance to zero (outstanding balance stayed the same after settlement) OR close the account. And interest keep stacking up again.