Still Paying for data

A few weeks ago I complained about being charged for data even though I have a 500MB data bundle. This is still happening. My bills are going through the roof because people there are not assisting me to sort this issue out. Last time they said they would refund me R315.03, call number 861763. You should be refunding me the data used not the data plan that you forgot to charge me for. Got my September bill and this refund doesn't even reflect on the statement, but this time I am being charged for my data bundle and data used when I don't go over the 500MB bundle. can someone call and help me fix this once and for all