Vodacom Double Charged Me

I recently installed Vodacom Fiber in my apartment (4 June 2019) I was forced to choose Vodacom as its the only ISP for my complex, as per their special for that month, the 1st month would be free then continue paying as normal, today (1 Aug 2019) I have been debited R1499, I called them two weeks ago as that when we got our 1st bill, they said they will investigate and call me back, no call since, Vodacom please return my money as you should have just debited R699 Only