Poor performance

Good day,i have recently been handed over to a collections company by Multi choice,after cancelling my dstv subscription months ago via their call centre i was really surprised to be getting a call from a collections company saying i was behind,i find this very odd seeing as though they debited my account every month,so obviously when i cancelled they stopped the debit order from my account, now i am suddenly months behind, i find this extremely unprofessional and a pain to suddenly be handed over for poor work performance on multi choices part, people be weary when dealing with them, i have told them i will not be paying a cent