Price Lock Refund

I was overcharged R3000 by Multichoice after I took up the price lock deal. I first called last Thursday (5 March) and was told a refund would be processed, but I still haven't received it. I've phoned a number of times, the last time I spoke to Nikita at the call centre and she told me it must be a "hold up at the bank". That can't be possbile. Please help.