MTN NETWORK IS *****ING MY ACCOUNTS

I NEED SOMEONE HO CAN HELP ME , I HAVE BEEN REPORTING THIS ISSUE .MTN IS KEEPINH ON DEDUCTING MONEY IN MY BANK ACCOUNT, WHEN I AM CALLING CUSTOMER SERVICE THEY CONFIRMED THAT I AM ON PREPAID ACCOUNT, THEY KEEP ON CHANGING DEDUCTION DATE , AS WELL AS THE AMOUNT, WHY MTN IS KEEPING OUR BANK DETAILS SO THAT THEY CAN ***** .I AM REALLY TIRED OF THIS THING BECAUSE EVEN IF I WENT TO THE BRANCH THEY SAID .I AM ON PREPAID .