Worst service from MTN

MTN has been deducting R139.22 (INSURANCE PREMIUM MONITOR24H ********** ********** CNPA8) for the past 24 months from my bank account regardless after writing letters,sending emails without luck asking them to stop deducting that amount since I'm done paying off the laptop and i don't want to continue with the insurance and recently they have been deduction R125.10 ( MTN SP A ********** ********** 600) without any contractual agreement. A year ago I went to MTN Kollonnade Pretoria to ask for assistance with the issue of discontinuing with the premium and they told me that they can't help me, i need to call the MTN contract number but i did that and they seem to deliberately ignore my please. What will it take for MTN to stop them from taking my money as they please. It seems that they are entitle to my money i work hard for.