Mtn cannot call back their customers

I wish to revert back to my standard plan of 299.00 per month. I filled in the migration form and requested some one to call me back as to complete my request. I received a ticket number *** and was advised I should call mtn as they cannot call a Sunday. I tried calling today and simply cannot get through to speak to an agent. I don’t know what else to do as I just want to down grade to my previous plan :-(