MTN.....what is the ****** Business??

My mother is 81 years old. She has a top op account at mtn but the last 2 months MTN starte deducting a lot more from her debit order than she signed a aggreement for. After we looked into the matter there were a sms send to her with the topic "Minkey business". When we called MTN they just said she had to replyon the sms "no" or "opt out" other wise they automatically sign her up from what ever it is. This was not her agreement With MTN and it seems they have access to your account to make changes without your permission. We have been on the phone with customer services and she has been to MTN shops. They assured her everything is okay now. After 2 days she got another sms from this ****** Business. We are very dissapointed in MTN's handling of this account. Just be on the look out for this on your accounts. The sad story is that she had to pay R100 more every month other wise they will give her over as bad debt. This is really not acceptable.