Overcharged by mighty vodacom

I am really getting annoyed at the level of service I'm getting from vodacom. Few days ago I called with regards to my contract bill that has been overcharged with R216,44 and they told me it will be sorted within 3 business dats, and within those days I got an SMS stating that the error has been corrected. But to my surprise the mighty vodacom still went on to debit the overcharged amount. Can someone who exactly knows something about solving this issue sort out this mess.