Wrong account number supp****,and were handed over

Made an arrangement to pay R2000 per month, and out of good willing signed a debit order for R2500. Made all the payments to an account number they gave me, en then sent letters, which i never got, and handed me over, because they did not see the payments in the account it was supposed to go. Now, according to me, i am finished with the payments, and on my request FNB sent me statements which reflects payments of amounts I never made!! Now i am trying to sort it out with their attorney, which by the way dont understand a word im saying!! What can i do????