Mtn removes cap limit and help itself to my money!

A few years ago I opened two MTN accounts for my two sons - account No:A***.<br> This was on the basis of a set call + data bundle rate. Anything over and above their monthly limit they would have to purchase the airtime for themselves.<br> The costs have always been paid through my bank account via a debit order.<br> As the amounts were fixed as per the contract I very rarely bothered to look at the debit order at month-end.<br> Unbeknownst to me, MTN's usage limit somehow mysteriously malfunctioned/failed in August 2015.<br> My son's continued to merrily download FB, YouTube vids etc, without a usage limit.<br> This usage limit was NEVER changed by me or my sons. We wouldn't even know how to.<br> The call centre, when they eventually answered after a couple of hours effort, told me that it was my sons fault and that I would not get a refund.<br> My local MTN outlet in Longbeach Mall run by Donna Moatse acknowledged in writing that it was MTN's fault and that I would get my money back.<br> In total I have been overcharged by R5590.95!! MTN dipped their hands into my account and took this money from their own mistake. I've been told I will get a credit. I don't want a CREDIT for this - I WANT MY MONEY BACK!!!!