Unfair treatment

I am facing a huge and depressing challenge. I had a personal loanc with Capitec and ended up not paying my account well due to financial problems. My account ended up handed over to DMC debt collector between 2013 or 2014. DMC was nominated by Capitec Bank to collect monies on their behalf. They called me to make necessary arrangements we then came up to an agreement that I will afford to pay R500 every 25th of each and every month. I then grant them a permission to deduct R500 in my Nedbank account I gave them my account details. While the R500 was being deducted by DMC i was gurnished and at the same time they put a judgements under my name. Please note that I did not missed any payment DMC kept on deducting in my bank account. My last installment was on the 25th. I even received a paid up letter from DMC and deductions were then stopped since the account has been paid in full inApril 2018. In September 2018 i then received phone calls from HP Attorneys indicating that they were nominated by Capitec Bank with regards to my personal. I was shocked because the account was paid in full, I try explaining that to HP Attorneys but they refused to understand my expectations. They threatened me that they will garnish me because I refused to comply. I tried calling DMC and even sent them emails explaining that I am receiving threatning calls from HP Attorneys. They only responded that they will investigate the matter up until today I haven't received any response from them. Today 24 September2018 I received an sms from HP Attorneys thanking me for commitment for paying Capitec yet I never made any commitments for such payment.