SLEEPMASTERS billing and notificationis atrocious

I received a call after 5months of no contact that I still owed sleepmasters. First they couldnt send me a statement so I offered to go to the store on the weekend to verify dates since they couldnt send me statements. However, they were still calling me every hour despite this notification and I still advised i would go on the weekend so i refused to arrive at a settlement figure without first seeing their statement or invoice.

Eventually i went to the store and advised them I had received an sms saying to pay R118.40 monthly as settlement, which I did by paying R120. Come Tuesday I started receiving sms several times daily saying it was R1.60 short when it was actually R1.60 more! I'm still receiving this sms daily every few hours.

That was not all. I than started receiving also on Tuesday, another email saying I had agreed to a monthly settlement figure of R396.90 monthly. At no time have i agreed to any settlement and only paid the R120 based on their own sms notification to me.

So in 24 hours i have received 3 different amounts to pay from this company and when i ask for recordings of any settlement agreement I apparently made at any time i am ignored. The daily sms' and emails still continue with different amounts showing. This is harrassment due to their own incompetence. Which authority can I report this to behaviour to?