Istore payment not received!

I bought an IPhone on the 2nd of May online but when I purchased it a second order went through on my card for over R12 000. I contacted them and they said that they have nothing to do with it. On the 14th of May they called me to say that it was their mistake and that they found it on their financing side and I will be paid back. On the 10th of June they emailed me asking for the necessary documentation and I sent it to them. I heard nothing after so I emailed them on the 27th of June and had a live chat on the 6th of August and called again on the 27th of August. Everytime Istore says that they can see the mistake and will take it up with financing to pay me back and update me but it never happens! So fed up I have been so kind and I receive nothing not even an update. It is utterly disgusting I have waited almost 4 months!!!!