Appalling service.....refund run around

MTN debited R2075 from my account on Friday the 27 of Feb. When I went to the Dainfern store....they acknowledged the mistake (over debited by R877). When I requested a refund I was told they can't help as they are just a store and not a service centre (I must go to Fourways) or call. Decided to call, spent 28 minutes on the phone and I was told that I paid extra- disputed that because I don't make cash payments. They will log a refund and it will take 72 hours(should be paid to me by Monday 1 March). As from Monday I have been receiving messages that my query is logged but no refund. When I called they said Wednesday. 2 March I got a Facebook message from them saying it might take another 5 days. I am so irritated at how unprofessional they are. It should not be this easy for them to make such mistakes but take so much time for them to rectify. To me R877....is alot of mine. I have things I could not pay because of this mishap