Overcharged - no response to case opened

I have been with Telkom for about 5 years now and previous to that I was with another company meaning that I know how an upgrade works. I have 3 accounts with telkom, I upgraded 2 of these accounts in May 2018. The agent explained to me that I will not be debited for these account month end, but will be paying the new installments with a pro rata end of June 2018. This was no news to me, I knew this and agreed. Then end of May came and they debited for all 3 accounts, which was not supposed to happen. In the beginnig of June I received my statement showing the amount to be deducted end of June will be the new installment and the pro rata, as it should have been. Only, they have already taken money that they shouldn’t have and now they still want an additional R2500. I spoke with a lady online on telkoms customer service as I could get through via telephone. It was clear that she didn’t understand what I was explaining. I then went to the Telkom store in Cape Gate. The lady looked at my statement and agreed that the amounts aren’t right. She opened a case. End of June came and the deducted the R2500, I went to Telkom CG and asked how far the investigation is, as I can’t afford that much money. The agent advised that the case is still pending. I then reversed the debit order. To this day I have not received a call from Telkom trying to resolve the problem, I have however received a statement showing my account is paid (not possible) and numerous sms messages threatening to block my usage if I don’t pay.

Well, if Telkom doesn’t resolve my problem I am going to report them for theft as they keep trying to debit my account of the R2500.