Overcharged Account

I had a garnishee order against my salary by the company from August 2011 to November 2013. On the 10th of December 2012, I requested a balance of what was owed on the account. I received a confirmation that the balance owed amounted to R5542,90. To my surprise I had to pay an amount of R750 per month, and also extra R750 that they claimed was arrears for November 2012 which was paid. I then tried to call and tell them yhat I believe that I have been overcharged that is when I realised that the reference number supp**** to my company was wrong instead of FR1669 it was FR1699 which they themselves supp****. It took months of frustrations to get them to sort out. In December 2013, they then send my company a letter to stop with salary deduction. I then asked for a refund because I knew that I have been overcharged, I expected to be refunded by +_R4000 which I believe was the amount. I was only refunded an amount of R1257,00( may be few rands difference). The rest of the balance was supposed to have been paid back to me but to date after couple of emails, I have not received anything. The last email from Annie to myself was on the 25th of April 2014. I just need my refund.