MTN unsolicited MOMO advertising .

For the past few months I have been bombarded with MTN MOMO messages . I have never gave permission for them to send me this messages. I can also not find any way to unsubscribe from this *******. I have unsubscribed thru consent settings from all their marketing ******* but the MOMO messages keep on coming. I had the same telephone no as long as MTN is in existence in SA. I think its time to severe my ties with this company when my current contract expire. Cannot wait.