Contract not cancelled even after obtaining a ref # in MTN Constantia Village Store

If I could give a zero or minus star rating, I would. I have created a Hellopeter account solely for this purpose. For the first time in my 46 years of existence, I am compelled to write to Hellopeter. I cancelled my data-only contract ***) 3 months ago at the Constantia Village MTN store in Cape Town (ref #*** - I have a reference number given to me on a printed sheet from the store that apparently means nothing). This is not the 1st time that I cancelled an MTN contract (I wish I learnt my lesson the 1st time, but one never does), this time I did because once it expired, they did not notify me - as they say they will, 1 month before it expires; resulting in me paying more than 300% more on a contract that had lapsed. I eventually went into the closest store in my area after trying unsuccessfully multiple times to cancel via the call centre number 083135 (they deter you by keeping you in a queue for more than 30 min and then dropping your call shortly after they answer or when they transfer you to retentions, or dropping your call when you don't want to be 'retained'). So after going into store and getting a reference number on a printed document as proof of my cancellation, they are still debiting my account 3 months later at >300% of my previous contract value. After almost 2 hours and waiting almost 30 min on 3 separate attempts after each other, because of the very same reason as above, Carmen (operator) tells me that there is no way any store can cancel my contract, I must call the call centre (who do their best to avoid you, especially if you are cancelling - miraculously, when you want to take out a contract or upgrade, you don't have a problem). NOW, she assures me that my contract is cancelled, after I already did it 3 months ago with a ref #; but wait, they are not going to reverse this month's debit order, they have to debit me again at the end of this month for the 'last' time first. This is the most disgusting tactics I has ever had to endure by a service provider - ******* and bullies indeed. Is there no other route one can take to stop this, that won't cost me more thousands?