I upgraded my contract on 8Jul

I upgraded my contract on 8Jul. I only noticed on the 17 Aug that the data I got os not what I agreed on. I informed mtn immediately. They have not responded to my query since then. I only got 40gb instead of 100gb. When I called them, they say it's only their service provider that can help me and said they have escalated to them. They have given me numbers that do not work. I have no data as in now, Mtn is not doing anything about my query, they don't care.