MTN - False Advertising

About two months ago I had a phone call from MTN wanting to do a migration on my contract. I was guaranteed that the migration will save me money. I was totally happy about that, but when I received my first bill after this phone (and migration) call my bill went from R464.43 to R664.43. So I have beg the questions?? How is this migration saving me money? I have made numerous calls to MTN asking them to sort this account out as this is not what was discussed over the phone. On three separate occasions I not only asked the sales representative BUT her supervisor that my contract will not me more than R380 a month and they guaranteed this to me three separate times. NO one has bothered to call me back or even rectify my account and now my budget is completed *****ed. This is pure false advertising. I request that someone from MTN phone me back very quickly or this will go to the ombudsman. I don't see why I have to fight. This is not what I agreed to. I agreed to R380.00 a months, saving me money!!!