DATA USAGE AMOUNT CHARGED!!

I have a Smart Broadband Wireless 20Gb deal with Telkom since February 2018.( ********** 821) This includes 20 +20gb Day and 20+20 Gb night data for R532.89 per month. This is a "capped" deal . On my account for August , R500 was added to my bill for extra data usage for that month. After enquiring about this, i was informed that this amount was added because i used more than the allowed 80Gb for that month. But my data deal was capped up to July 2018?? and it is now suddenly uncapped!! Who changed this at Telkom?? The same happened in Sept 2018 and again R500 was charged extra including CLI presentation fees which i did not request. I am struggling to get this sorted out with Telkom and after the assistant assured me it should not happen again.... it did!!! What now??