Incorrect monthly deduction

I signed a 24 month TopUp contract for a sim card for a ****le on 2 Jan 2014 (2Gig/mnth). The agreed fixed amount was for R109.00.<br> There were problems with this contract from the start. Eventually Shivek Devlall managed to sort it out and the correct amount of R109 was deducted from my account once the overcharges had been resolved. My last email from him is dated 25 June 2014.<br> In June 2015, the amount taken from my bank account suddenly changed R115 per month which I queried at Noordhoek branch but was told that all data costs had increased. And then the July 2015 deduction was R275 instead of the agreed contract amount of R109. MTN Noordhook branch could not assist.<br> Nosithembele Nabo on the call centre told me someone at MTN had changed my contract from TopUp to open in June 2014 and that she'd arrange for my contract to be migrated back to TopUp and for credits to be passed.<br> When I followed up with her, having received a new statement from MTN showing that now they were going to deduct R136.50, her response was to tell me that MTN's billings department say \there is no credit due as a transaction was made on your phone". Who can I deal with so MTN deduct the agreed amount?"""