MBD (Munnik Basson Dagama Inc)

I have been harassed by MBD (Munnik Basson Dagama Incorporated). I get numerous calls from them with different numbers. When you call back the line goes dead or does not answer at all, Their staff also work from home and they all call from different cellphone numbers. They do not communicate with each other and then you receive calls all the time at least 3 to 4 times a day! A payment arrangement was made with them which I have paid every month and always pay on time. Nevertheless I still get harassed at 7h00 in the morning continuously. All these calls and sms's they add to their costs on my account i.o.w. they make money by just calling and not even answering the phone. This is absurd. This morning they had someone calling me and requesting that I confirm my details to them (This person was calling from a cellphone number) so of course I said that I dont feel safe to confirm personal information over the phone if I have no confirmation of the persons true identity or that they are really calling from MBD as they claim to be. Then they went on and shouted "So you are refusing to co-operate!?" where I responded to "No"and then hung up. If people dont have decency talking to me over the phone, they can go F themselves! Call me from a landline or send me statements via email and I will attend to it. But NOTHING is changing. I have complained about this several times, but they just dont give 2 sh*ts about it.