After 12 weeks the phone still doenst work

vodacom phoneds me and explain who they test the phones and how much it cost them to courier the phones up an down .<br> They said the phone was tested but nothing could be found wrong with the phone. As soon as i put a simcard in the phone it reboots. How can vodacom say there is nothing wrong. The lady said she will phone me back on 11/08/2015 and never did. What should i do ? . The problem is still there. what do i do now. The phone still doenst work