charge me subscriptions that I signed for

I upgraded my contract on 20/06/2015, the package that I chose was R149.00 as advertised on the MTN June 2015 deals catalogue, after a week I received an invoice from MTN dated 20/06/2015 and the amount was R179.99. I called 808 to find out what is wrong but they advised me to go back to Lakeside mall because they captured wrong information.<br> <br> I went to Lakeside with the copy of my contract and spoke to Esther Sibeko who confirmed that the contract was captured correct. She called 808 and spoke to Shaney (***) and she told her that it was the price increase that was effective from 13/05/2015 and customers were notified by sms on 15/042015. I know and understand about the MTN price increase but I don't understand how it affects the June 2015 . I want MTN to correct this mess and charge me for what I have signed for on the contract that I took on 20/06/2015.<br>