Harassment from debts collectors

I cancelled my membership, I made an arrangements with them to pay R200 monthly. Now they handed me over to two debts collectors and I'm paying as my arrangements. They hand my acc to Landou Attorneys and Recovery something. Now my balance is R561. Landou Attorneys are harassing me day in day out, and they have wrong balance of R1261. I'm tired of explaining to them and they see on their system.