Harassment by NuDEBT

I have a few contracts with Telkom and due to changing jobs had to change my debit order date but for the past few months its been a absolute nightmare. Telkom are not debiting my account, and then I do a eft payment and before I know it I am handed over to NuDebt. I get daily emails/sms from NuDebt and feel like this is harassment, how does Telkom operate?? Hand someone over after you made the error of not debiting and I have been told by a Telkom employee that the date chosen is a problem in terms of debit orders.. then why allow it?? Now you have suspended my line and I am at the point where I will not be renewing any of the contracts that I have with telkom as this is pathetic. I phone NuDebt and get told the payment takes 5 days to reflect when I am paying via a link that they have sent me???