Harrasment Calls

I have been getting numerous calls since about June claiming the last payment that I made was in March. I sent through proofs of payment for April and May to Tshegofatso Matomela (whom I am told no longer works there). Even after sending all the proofs, I still received phone calls and once I advise the consultant that I had sent through the payments then I keep getting the same response "I will follow up", I get to hear this line 6 times a day, everyday. On the 16th October I decided to write a complaint to FNB credit card division ref ********** and received the same feedback, last payment was in March, so I once again sent all the emails that were previously sent to Brooks & Luyt and then there was silence. I then lodged another complaint stating that I am still waiting for feedback from FNB, still nothing to date, meanwhile these harassment phone calls from Brooks & Luyt have never stopped. 22/11/2017 at 13:40 I received a call from Brooks & Luyt number ********** asking for payment, I advised that the matter has been referred to FNB of which they told me (very cheeky) that FNB is their client and they have been directed to collect payment. I am getting 6 to 7 calls a day, even on the landline at home. I do not know where to turn to since FNB is not assisting either.