Cancellation

I cancelled my Cell c contract on 10 Of July giving CELL C 3 MONTHS NOTICE, RECEIVED EMAILS AND CALLS CONFIRMING THIS, NOW IT IS OcTOBER AND CELL C PHONES ME DAILY SAYING I NEVER CANCELLED, WHAT IS GOING ON NOW IM CHARGED FOR OCTOBER WHICH AN OPERATOR ALSO **** TO ME ABOUT, SAID I WAS ONLY CHARGED FOR SEPTEMBER, I JUST OPENED A STATEMENT AND I WAS CHARGED FOR OCTOBER????? WHAT PATHETIC SERVICE HOW MANY TIMES MUST I EMAIL OR PHONE TO GET A SERVICE I PAY FOR????? THESE PHONE COMPANIES MUST THINK CONSUMERS ARE STUPID?????????