Unusable prepaid airtime purchase Not Refunded yet

I tried raising this issue online on the Cell C website as well as in store and even sent through stamped bank statements that I had to go and obtain as well as screenshots from the internet banking app to explain the process that lead to an accidental and unusable prepaid airtime purchase of R500.00, I have had absolutely no assistance or feedback in spite of various communications sent between 18 and 21 August in respect of an accidental purchase on 17 August. The principle is simple as far as I am concerned. I did not intend buying the airtime in question, as I am a Vodacom prepaid customer and can derive no benefit from having Cell C airtime, linked to a Vodacom SIM card. Cell C therefore has my money and I should be able to get it refunded. There is no use asking the bank to \reverse"the transaction (which I did the very next day after the purchase) because the money was already with Cell C. I am however having no joy in getting it returned to me and it has already been three weeks.. I am really disappointed by this complete lack of service or assistance"