Phone calls made on a SIM MTN lost

So... <br> I send my Tablet in for repairs to Meadowdale Mall MTN <br> - Get it Back without a my SIM <br> - Meadowdale tells me to just do a SIM swop and the old SIM will get cancelled<br> - Request a SIM swop, from a Klerksdorp branch in June 2015<br> - New SIM never worked <br> - So I keep my tablet switched off, because it doesnt work<br> - 6 Months later I get a bill for R1400 in phone calls <br> - Phone my number (Number of the Tablet which is switched off), and a guy picks up and says he got the SIM with the phone he bought. Somehow he got issued my old SIM<br> - No assistance from MTN <br> - Now you reply that I should go get an affidavit from the police so the ***** dept can investigate! <br>