been billed for an expired contract

My 1x contact with Telkom mobile expired on the 6th of December 2015 and i was paying R365 per month for it. On the 3rd of November 2015 i went to telkom shop in Centurion n fill in a consumer request for contract and service cacellation. I got a call from telkom agent for an upgrade n i told them no. Because i have requested a contract cancellation. I have just been billed R1054.00 for January. Why have I been billed if I requested a cancellation. How do know I can afford it because my contract was R365.00 not R1054.00. Can you please resolve this issue a.s.a.p