ADT SECURITY PLEASE STOP DEBITING MY ACCOUNT, I CANCELLED MY CONTRACT MONTHS AGO!!!!!!

On September 2019 I called ADT security to cancel my contract and was informed that I need to put the 1 month cancellation notification in writing, I did this on the 4th of September. My last debit order was deducted as expected. ADT continue to debit my account despite having provided notice for cancellation and reassurance from it's Finance staff that they have cancelled the contract. Each time I call I'm told a different story of why they keep debiting my account. In November when I called I was told that I could go ahead and reverse the debit order as it will take them weeks to do so from their end. This month they debited almost R1000 more money than what my subscription was!!!!!! I was an ADT Security client for many years and I had never missed my monthly payment but to receive such an appalling treatment because I can't afford their services anymore it's a disgrace. I have comp**** with ADT Security contractual cancellation requirements, why can't they? ADT Security please STOP taking money I don't have from my account!!!!!