Harassing messages, change in amount owed

Hammond Pole have been absolutely awful. They send me threatening SMS messages regarding payments when I have always paid on time or before due date. Today I received an SMS warning about late payments followed by another SMS stating 'to prevent a summons I must ensure payment is made.' It was made days ago and my account is now paid in full. I have had 3 conflicts of information regarding amounts owed: 1. Sifiso Mavimbela told me the amount owing was R4000. This was paid Aug 2016 in full 2. Only to be told by Simone Renze that I now owe another R9,580.73 and coming to an arrangement of R800 per month which I have paid each month religiously. 3. On 25 April I asked what amount was still owing and Nwabisa Sibanda advised it was R3830.22 4. If I look at the amount of R9590.73 as advised as the amount needed to be settled and that I have paid R800 a month for 12 months my account should be sitting in credit as I have paid R9600.00. However Simone Renze states I still owe R1790.69 which is clearly not correct.

This account has actually been paid in full. If anything Hammond Pole owes me R9.27. Since my email detailing this yesterday I have had no response from any of those copied in on the email and instead have received 2 SMS messages today with threats.

Just honestly horrible how they treat people.