Service Cancelled in May 2018 But Telkom Account Handed Over for Collection in September

In spite of canceling my subscription via Telkom's Online Portal, I still receive monthly accounts billing for the service and today received notice that my account has been handed over for collection. How is this possible when your system sent a confirmation email on the 31 st May 2018 that the service cancellation was accepted? It is because of this bad service that your subscribers want to cancel their subscriptions in the first place...