billed after contract was cancelled

WE HAD A CONTRACT WITH TELKOM/8TA , CONTRACT WAS CANCELD AND AFTER THE 24 MONTHS THEY STILL BILLED US FOR DATA . BEEN PHONING AND SENDING MAILS FOR 3 WEEKS AND NO FEEDBACK <br> IS IT LEGAL TO BILL CUSTOMER AFTER CONTRACT WAS CANCELED ( 2 MONTHS LATER ) AND THEY ALSO BLACKLISTED US FOR NOT PAYING THE BILL ? AFTER MAILS AND ALL MAYBE TO GET LEGAL ADVISE WILL SORT THIS OUT ! I WILL NEVER TELL PEOPLE TO GO TO TELKOM OR REVERE THEM ! AND I WILL ALSO GO TO THE NEWS PAPERS ! THIS IS NOT LEGAL WHY MUST I PAY FOR A MISTAKE THEY MADE AND IF I NEED TO GET A LOAN FOR ANAYTHING NOW THE BANKS WILL NOT HELP ME BECAUSE THEY BLACKLISTED ME ! I DO HAVE ALL THE FROOF THAT WE CANCELED THE CONTRACT ON 31/08/2015 AND THEY BIILED US IN 31/10/2015<br> WILL TAKE LEGAL STEPS