MTN overchercharging when you upgrade

Good morning. I am so disappointed with my service from MTN. About 1 and half months ago a consultant from Constantia Village MTN phoned me and said I was ready for an upgrade. I asked and even have proof via whatsapp that I asked whether there would be pro rata fees or an immigration fee. ( 2 years ago when I upgraded MTN wrongly charged me a migration fee which also took me a while to get reversed). I was wary to upgrade because of my bad experience with the extra charge last time so I kept asking whether there were extra fees . The consultant assured me there would be no fees! So I upgraded. And true as bob when my debit order came off MTN had triple charged me!! Now the fight begins to reverse this charge. It has been a month now and my debit order is about to come off and nothing has been done. The consultant at Constantia village ignores my whatsapps, the person on messanger via Facebook ignores me now as well. The champions via the call centre tell me to go to the branch. I am at my wits end.What can I do to get some service and get this charge reversed. Is MTN running a **** here?