MTN Shifting the blame

MTN refuses to accept that their own marketing department sends unwanted marketing adverti*****ts to their customers. Despite numerous requests to OPT out, unsubscribe and cancel all SPAM, they continue to send me their adds (like "Pay extra R15 for 30MB") *******. Their most recent response actually claims that they are no sending the spam, but the only the carrier is able to send popups and 141 recipient spam messages like those I have received. MTN is lying blatently in order to continue their greedy marketing campaign and we users can do nothing about it. Extremely disappointed in you MTN.