MTN "upgrade" results in double amount being deducted.

I was recently informed by MTN that I needed to upgrade, as the package I was on had been discontinued. I comp****. However, when I received my invoice last month, it still reflected the old amount. I visited the Clearwater Mall store and was told that the new amount would only apply from this month. Surprise, surprise—this month’s invoice is exactly double! I returned to the Clearwater store and was told that the “new amount” would only appear next month. But why two identical amounts—both the new contract price—would be deducted this month made no sense at all. While I was there, a woman in tears approached me and showed me her account—also double the amount. I even went into Customer Support this morning, but still received no clear or understandable explanation.