DEMAND FOR PAYMENT THAT I DO NOT KNOW ABOUT

I have been using cell c for many years and i trusted them. I WAS TAKEN BY SUPRICE LAST YEAR WHEN I RECEIVED A CALL FROM SOME CREDIT COLLECTOR TELLING ME MY ACCOUNT HAS BEEN HANDED TO THEM FROM CELL C.I DO NOT KNOW WHAT IS IT I AM OWING AND HAS BEEN TO LOCAL CELL C SHOPS AS WELL AS CALLING CUSTOMER SERVICE . NO ANSWER TO WHAT IT IS I AM OWING. I CURRENTLY GET MY STATEMENT VIA E MAIL AND THIS OUTSTANDIND AMOUNT HAS NEVER BEEN COMMUNICATED TO ME BY THE COMPANY. VERY DISAPPOINTED. THERE IS NOTHING FRUSTRATING LIKE GETTING CALLS FROM STRANGERS ALMOST DAILY THREATENING.