Communication to client?????

I did an upgrade via Glocell and then duly cancelled the upgrade. I spoke to consultant there and he managed to reverse transaction and change contract to a Pinnacle 50. However, as there was already time that lapsed, he suggested that I use the data as i would be charged for this on a pro-rata basis. Had a look and there was "data" and "black data"

Utilised the data and to my horror discovered that the data was finished, black data balance of over 5G still remained and I was then presented with an account of over R1800 for data usage???

Have been trying to get this sorted, but unsuccessful. Numerous mails to the person who assisted me and it appears that they are going into a black pit at Glocell????

1) Who, in their right minds, would incur such costs for Data? 2) NO-ONE from Glocell told me that "Black Data" is accessed differently or even how to activate and use, so, if this was omitted, who would think that there are special procedures to activate and utilise?

Glocell, PLEASE can I get someone to assist with this?