MBD consultants keeps calling me unnecessary

I have an Edgars account that is behind due to unemployment. I gave made arrangements to pay R250 each month. Even though I do pay they keep calling me and smssing me sometimes several times a day. What is making me angry is the fact that I have paid and they still call me. Those calls end up on my account and I have to pay for them. A consultant told me today that they will keep calling until I arrange debit order payment. I will not arrange a debit order and have told them that numerous times. I transfer the money each month. Furthermore I asked for a detailed statement which I was denied. I receive sms from them regularly asking to pay before the 30th of April which is long gone. We are in November already. The letters they mail me had the same mistake. Their consultants are rude and unprofessional. This is really going against my rights. They have no reason to keep calling me if I have paid especially when I have to pay for the calls and have no right to try and force me into a debit order.