Debit order keeps going off

I cancelled my dstv subscription 4 months ago and up until today they keep taking my money. I have to go to absa every month end to do a reversal which costs me money petrol and time of work. Everytime multichoise just chances the reference number and then the debit order goes off This is ridiculous how can i pay for something i have not used for months. No wonder i cancelled because your service is pathetic