african bank service is bad

i had a loan with African Bank due to non payment it was handed over to concept recoveries , i settled the loan with Concept Recoveries and the discounted the debt and i payed 90k, now african bank keeps on debiting my acc they saying they want the remaining amount and i payed the amount that was discounted so i dont understand. or i should take them to the Obdusman maybe they will explain what is their problem.