Hoodwinked by outsourced company I thought was MTN

I was contacted in November by what I thought was MTN offfering me an extra data package that would cost R30 more a month for 80Gbytes of data, as I had been running out of data on my package. I checked with the person that my current contract would not be changed in any way, but only the extra data would be added, and was assured that this was so. Now I find that they changed my package so that I have no minutes! I realized this only now as apparently I had available minutes from my contract. Now I cannot change this back until February! The MTN agent explained that this was done by Rewardsco. an outsourced company, and not by MTN, as I thought.