*****ulent contract

I had a cellphone contract with MTN, when it ended I upgraded to a data only option, when that ended I adamantly said I don't want a contract anymore and would like for my Sim to be prepaid when someone from mtn called me to interest me in an upgrade. 2 months after I told them No they continued to deduct money from my bank until I went and stopped it at the bank, I even called MTN myself to tell them to cancel the contract to prepaid at the end of the contract. I noticed that I have been getting bills from mtn, when I opened I realized that I am owing mtn because every month I am billed R19 from a new contract that they gave me without my knowledge and I got this information after I spent all morning on a call last Tuesday being sent from pillar to post by mtn and never got help. MTN gave me a contract without my knowledge and still this morning I got another bill from them after their *****ulent action. They do not want to cancel their *****ulent contract and debt on my name. The said Sim doesn't even work because they say it has been suspended, how do I owe them for something that doesn't work from the time I said no to a contract, for about 7 months it has not been working and they have been piling up a debt for that 7 months of a non active Sim that has been allocated a *****ulent contract. On top their bill also has a 132 from the time I stopped their transactions at the bank when they continued to deduct after the contract ended. Mtn is ****ming me