Appealing experiance at the Northgate branch

I want to MTN at Northgate on th 13th of May, I wanted a contract phone and to get data via contract, I was told to get the phone and data on a Wednesday which did, I they gave me an excuse to why the data Sim wasn't working and told me it will work after 24 hrs, I went back on a Thursday still the card was not working,. I decided to go back on saterday and it was the same excuse.. Which was the system is new and it si slow, it can't pick up your card, through all of this there's no phone calls on their side and I'm the one that has to go back for answers. I finally asked them that since I have traveled back and forth from my place they need to give this Sim for data which they did. Once again the Sim was not working, this was day 8 and I was so frustrated because that I went back and told the that they should cancel the card since it is not working, the guy agrrlreed and took my number and email and told me that they will let me know when everything is canceled and finalized. Today on the first of June I get a message that over R800 has benn dectucted which clearly says that they did not cancel the Sim for data. I have received the worst service from this network, this was my first time getting a contract and the e experiance has been horrible. I now have to go back to those same people and ask them why my contract was not canceled, I'm just really appalled by this service it will take forever to end this, going back to that place when I had gone back for over 4 times too just plead with them for my data. Please handle this with great urgency