IS THIS REALLY POSSIBLE?SYSTEMS CAN NOT ACCEPT NEW CREDIT CARD

I TOOK OUT A NEW CONTRACT IN JAN. ALSO GOT NEW CREDIR CARD FROM BANK. MTN IS STILL DEBITING OLD CARD , SO FOR THE LAST 3 MONTHS I HAVE BEEN "THREATENED " ABOUT NON PAYMENT. FOR LAST 3 MONTHS HAVE TO TRAVEL60KM AT TIME TO PAY ACCOUNT. LOCAL BRANCH TRIED FOR 3 MONTHS TO CHANGE CREDIT CARD DETAILS, BUT SYSTEM REFUSE TO ACCEPT CHANGE. IS THIS A GOOD ENOUGH REASON TO RETURN FONE AND CANCEL CONTRACT? JJ