OVERCHARGED AND NOT GETTING ANYWHERE

I am disgusted with their service. I had a data sim card contract and the 24 months has now passed, thus the rates are now charged out of contract (prepaid), but my problem is that the original data sim was only for 1Gig. Now suddenly they load and charge me for 3 Gig. When I contact them, the contact centre says, yes they can see it and escalates it to be investigated, but nothing happens. The MTN branches can also not "see" on their system and advise that I phone the call centre. Another month has passed and they are charging me the same AGAIN!!! And I don't even use the 3 Gig! When I asked them to cancel the sim (stop the number) they said it would take 48 hours. That was 2 weeks ago and it hasn't been stopped either!!! It is sickening that they can ******* people in these most difficult times! Yes, my debit order DOUBLED because of this!! And they just don't care, because they get their money!!