Extremely poor service from MTN

I recently upgraded my package and the new package was supposed to load on 27 August. A smaller package was loaded and I have been trying since 28 August to have the matter resolved with countless calls and e-mails to their call centre. I was even assured that the supervisor Tiny would call me on the same day... Two weeks ago! No call from Tiny. In the meantime I am paying a higher price for a smaller package. I've visited an MTN branch, but was told to contact the call centre as the upgrade was done via the call centre.