Cellphone Account Cancellation

I have had problems with Telkom for over almost 2 years now! I took a Samsung tablet from them a long while ago on contract. Unfortunately, I lost the tablet and had not been using it much before losing it - hence, I didn't know the telephone number. I honoured my contract with Telkom (finished the 2 years standard contract) and then requested them to cancel my contract in October 2016. The contract was not cancelled. They continued debiting my account. In January 2017, I telephoned them, whereafter, they sent me a cancellation form. I duly completed such cancellation form and advised them that I did not remember the number and that they should use my identity number instead to get the telephone number from their system. I then went on Maternity leave in January 2017. Whilst on maternity leave I noticed that they were still deducting monies from my account. I then went to a Telkom store in Greenstone mall and asked them to cancel it. I was asked to complete a cancellation form (again) and fortunately, the shop assistant was able to get the telephone number from their system. To my utter dismay, I see that they are still debiting my account. Not only that, my credit profile has since been messed up! In August 2017, a friend sent me the number in question, which I forwarded to Telkom ********** but still nothing ever happened. Having written to them several times and gone to a store physically, I do not know what else to do. I feel that I have exhausted all my means. Just recently, Telkom debited over R1,700 from my account. Each month, I have to call the bank to and request for the debit to be reversed because the debit amount varies.from month-month for some strange reason.