No refund on R483 overcharge after 8 working days

I am currently on hold, waiting for someone in your customer service division to answer my call. So far I have sent 3 call me back requests through the app, the first one at around 9am this morning, to no avail. I have now been on hold for 12 minutes and counting. On the 31st of March my first debit order went through, for R983.47, instead of R500.07. After an only slightly lengthy wait for someone to answer my call at that stage (on the 1st of April), I got through to a lady who confirmed that it was an error, and that a refund would be reflected in my account within 5 working days. That was 8 working days ago. And now the line has just gone dead without anyone answering my call.