Incorrect billing.

I received a bill for over R29k for 60 Gig used in data. My monthly usages is under 3gig as I only pay R159 per month. The interesting part is that this 3g card is was removed form my PC when my PC fell on the 26 May 2015 and the latter was sent for repairs. Still I received this whopper of a bill. After asking for it to be investigated, I got told that the billing is accurate to the data usage. What data usage???? Apparently the IMEI number linked to this 3g card was used? What IMEI number? It is a stand alone 3g card.<br> <br> What the hell?