UNFAIR TREATMENT AND HARRASMENT

My name is Lungisa Dikimolo I D no ********** 533084 and I had a credit account with Capfin and the contract was for 6 months. I then approached my bank to consolidate my accounts including this one. On the 20 September a payment of R8000.00 was paid to Capfin via EFT from Nedbank and the next day I was sent a message by Capfin ackonlewdging that " thank you for paying UP your loan ." on month end 25th September I discovered that the amount of R800+ was deducted from my bank as an instalment, and I simply reversed it. From then I have been receiving harrassing calls from their agents of being in arrears and again and again I explain to them but no one wants to listen to me they cl;aim that I still owe some money. Firstly I sent them their sms and that they have acknowledged my paid UP amount. My question here is why did they acknowleged that I have paid Up and again, even if I did not pay up as they insinuate how am I in arrears when I have paid R8000.00 way before my contract ends. I am very much depressed and I want Capfin to repay for the harrassment I have been caused because I almost recieve 3 to 4 calls per day from different people despite my explanations. If they can check my account I ma sure I have never defaulted with their instalments. I want the person who sent the sms to explain as to which account was paid UP or they do not know the meaning of the term. Paid Up . I am very disturbed about this . please help me