Mtn not giving me my refund!

Hello. I have a problem. On the 3rd of May, I bought roaming data, 1GB for R299. I paid for it through my bank card and the money was taken out, but I never received the data. My roaming balance remained on 0 Mb. I then called to ask for a refund, a case was opened and I was asked to submit proof of payment. I did so but the case was just closed without being resolved. I called again and another case was opened. The same thing happened again. The second case is now also closed. I still haven't gotten help!! They are just giving me run arounds!