SDK Attoneys are targetting people threaten them to blacklist them in Bloemfontein

This people have being harassing me for two week now after my Business account from FNB was tranferred to them, I paid outstanding amount to close the account but now I am the one getting emails and sms claiming that I owe them. I have sent them Proof of payment twice already and I have called them twice and they have same answer every time they will look into it.