billed for data that I did not use

Hi. On the 6th July I have received my autopage bill, with data charged of more than r1500. I have not been using the sim card at all. The card was not even in a mobile phone or in the router. But some how I have still been charged. I have phoned in 4rm the 7th July till 2day I am still phoning with no feedback. They have been telling me that my query has been duplicated . N then deleted. BT no feedback as to how I am charged 4 data that I did not use..