Vodacom and creditworx

I have been receiving calls from creditworx for months now. I will never confirm any personal details to anyone, regardless of who they are, unless I made the call myself and I am identifying why I am calling. Now I get told that for every call they make, it will be charged to my account. Firstly, I did not enter into any agreement with creditworx, therefore they have absolutely no right to even contact me. Secondly, when that account was handed over the outstanding amount was written off by vodacom, so where does creditworx get the right to now incur costs of their own? And thirdly, *******ly soliciting funds from the public is against the law, this coming from a so called legal firm. I am well aware that this is SA and people have the tendency to *****, but for a legal company to partake in such activities is disgusting. I am tired of being *********ed and threatened by creditworx. If it were the case where i didn't pay anything towards the account for years, maybe then they could have continued to do so. But could they please explain, how adding additional costs to an account that is currently being handed over and paid very slow is going to encourage the consumer to pay. Where would i get the money from if i am already struggling? Its strange how logic defeats some people and their business policies. I could just blatantly refuse to pay anything and they can see where they get their money from, but i pay what i can afford and this is not good enough, I wonder how many people they leave alone because they just refuse to pay, instead harassing the ones that try to do the right thing.