INCORRECT AMOUNT DEBITED OF ACCOUNT

I HAVE BEEN BILLED INCORRECTLY OVER THE PREVIOUS TWO MONTHS ON MY VODACOM ACCOUNT VIA DEBIT ORDER.I HAD CALLED TO LOG A COMPLAINT AND THE LADY THAT ASSISTED ME HAD STRESSED OUT THE POINT THAT THE CUSTOMER IS LAIBLE FOR ANY BILLING AMOUNTS AS PER THIER VODACOM CONTRACTS.THE LADY THAT ASSISTED ME HAD MADE MENTION THAT IT CAN NOT BE AN ERROR ON VODACOMS PATH BUT SHE HAD OFFERED TO CREDIT MY ACCOUNT FOR AN AMOUNT OF R600,WHICH I HAD REFUSED.IF THERE WAS NO LEGITAMITE COMPLAINT WHY WOULD SHE WANT TO OFFER TO DEBIT MY ACCOUNT.I HAD THEN RECEIVED A CALL FROM A MALE FROM VODACOM TWO WEEKS LATER WHOM HAD CALLED TO RESOLVE MY DISPUTE,HE HAD OFFERED TO CREDIT MY ACCOUNT WITH THE HIGHEST BILLING AMOUNT OF MY BILLING CYCLE,THIS OFFER I HAD ALSO REFUSED. IS THIS A QUICK FIX FOR VODACOM TO COVER UP THIER ACCOUNTS MISHAPS THAT THEY MAKE.I AM SURE THAT THIS IS NOT THE ONLY COMPLAINT ABOUT VODACOMS BILLING MISHAPS .I REQUIRE VODACOM TO PAYUP MY CONTRACTS FOR THIS UNPROFESSIONAL PRACTISE OF THIERS. POOR SERVICE FROM SUCH A REPUTABLE SERVICE PROVIDER IS UNACCEPTABLE.