PLEASE HELP

I called in March to cancel my contract and ended up opting for an upgrade. I waited a few weeks for the iPad to be sent to me and in the interim decided against it and requested for it to be cancelled and for my contract closed. The iPad got delivered to my house and I sent it back with RAM couriers the following day- 19/05/2015. I got charged for the month of May, June and July for this iPad in which I think is ridiculous as I never used it and sent it back immediately. When I called the accounts department they said to me that this money would be reversed. In all honesty its not worth the fight for this money back but when I received my statement for August I see that for this number my bill is R4800 ?? I've gone to Vodaworld myself to query this and I've tried getting trough to your legal department but no avail. This number wasn't even an unlimited contract so it's impossible to be that much. I'm not complaining about the service I've received but the actual processes in place to resolve such issues. Please can someone tell me who to contact to get this sorted ? The time for my debit order is approaching and this whole experience has just been so stressful and a mission.