Data billing

We haven't received any notification that data charges rose from 1 April from 0.25c tot 0.99c, only on 11/7/2015 statement it says out of bundle data charges have changed that's it! Nothing previously! So how can you charge so much without notifying us in any way only after enquiring we are told this? And how can outbundle 1g rate be R160 but if we go over contract bundle we pay per bite so 1 gig is more than R1000? Since April your strike started our data escalated and your prices rose and according to your contract we should have been notified via sms and or on paper but we weren't! I googled your price increase and on the 14 April it says your going to hike prices how can you charge from 1 April? You suspended us on 4Aug and activated us on 12aug but nothing has been resolved! We will not pay this price increase we weren't notified and it is unreasonable! Not even your statements from April to June says anything about a price increase and how can 9 gig example 9x160=r1440 be billed in bites R8910, how do you calculate that <br>