Overcharged every month with no refund

I was overcharged on my October account by R212 and was told that it would be credited to my account in November.<br> I received an SMS for my account balance in November and discovered that there was an extra R150 added (R300 for 1GB instead of R150) and the R212 hasn't been deducted. <br> I called twice on Friday 27 November to rectify this before I was billed but on the 30 November 2015, R600 was deducted from my account. I immediately called customer service and was told that the amount owed to me would be refunded in 7 days and that a confirmation email would be sent to me. Neither transpired.<br> <br> I called customer service again today, 7 December 2015, only to be told that the amount won't be refunded but that my account will be credited.<br> <br> It is unacceptable to overcharge my account every single month and say that it will be credited to the next months' account when it isn't.<br> <br> It is seemingly impossible to sort this out with customer service as every time I call it is \escalated"and \""forwarded\"" and nothing ever comes of it.<br> Kindly arrange a refund of the amounts owed before next months \""error in billing\"" occurs."""