Potential theft and ***** by telkom

Yesterday I received my statement from telkom for data sim card of 80 gig. July I was invoiced R209 which correct amount agrees. But for August am invoiced R251. I called 018 180 and 10213 no help. Today I went to. Branch in wonderpark mall. The guy did not help me at all didn't even access my account or gave me phone call telkom or call on my behalf. I tried use method request callback it does not work. This over charging without explanatios is just clear definition of theft by telkom. Now want cancel my contract with them I regret why renewed it last time