BAD SERVICE

I AM SO DISAPPOINTED WITH MTN CUSTOMER CARE,I TRIED TO RESOLVE A SIMPLE ISSUE ABOUT MY NUMBER NOT ACCEPTING THE WHATS UP DATA BUNDLES RECHARGE,AND I WAS TOLD THAT MY NUMBER IS ON CONTRACT WHICH I CANCELLED A YEAR AGO.TRYING TO EXPLAIN,THE AGENT INSISTED THAT MY NUMBER IS ON CONTRACT. SO NOW I AM NOT SURE HO TO SOLVE THE PROBLEM? OR SHOULD I GO TO VODACOM BECAUSE CLEARLY MTN CUSTOMER CARE CAN NOT ASSIST