WiFi contract

I have been billed over 2700 in May 2018 for something that was not my fault and still haven't received my refund to date after calling numerous of times and being told its with the billing department. On the 13 May 2018 I changed my package and the consultant at Trade Route Mall put me on the incorrect package and was supposed to reverse it which wasn't done so at that time it showed that I had 2 packages that was incorrect and I only picked it up when I received my invoice, I went in on the 23 June and logged a query case number ********** 8 and have been following up and had no assistance thus far it is becoming really frustrating as my money was debited immediately but takes forever to be refunded. I was told numerous times that a manager would call me and to date I still wait for the call. I want my issue to be sorted.