Product: Credit card or prepaid card

This problem is with my XXXX XXXX Bank of America ( BOA ) credit card. I pay my credit card balance via direct withdrawal from my personal checking account set up on line at the BOA website. The problem is that BOA is making unauthorized withdrawals from by checking account. 
On or around XX/XX/XXXX, I received my credit card statement covering the period of XXXX - XX/XX/XXXX, showing a total balance owed of {$2400.00}. On XX/XX/XXXX, I paid this amount in full by direct withdrawal from my personal bank account, one-time transaction. I have never given BOA the authority to make automatic withdrawals from my account. On XX/XX/XXXX, without my knowledge or authorization, BOA withdrew a second amount of {$2400.00}. When I was notified by email by BOA the next day thanking me for this second payment, I immediately called the BOA customer service number and told them that this second withdrawal was not authorized. The customer service agent insisted that I had authorized this second withdrawal because her computer indicated that I had. I informed her that her computer was wrong and I did not authorize this second payment. I was eventually referred to BOA 's credit card fraud unit. This second BOA agent apologized for the unauthorized withdrawal and told me that BOA was having problems with its computer and that many customers were experiencing the same problem duplicate withdrawals from their accounts. She assured me that this problem would be remedied and that the second payment would be returned to my bank account. The second payment never was returned, but I did not further complain as I assumed that my balance on the next statement would exceed {$2400.00}. 
On or around XX/XX/XXXX, I received a BOA statement for the period of XXXX - XX/XX/XXXX, showing a total amount due of {$6700.00}. On XX/XX/XXXX, I paid this amount in full by direct withdrawal from my personal bank account, one-time transaction. Early in the morning of XX/XX/XXXX, I received an email from BOA thanking me for a second payment of {$6700.00}. I logged into my on-line BOA and checking accounts and discovered that BOA had made a second, unauthorized withdrawal of {$6700.00}. The BOA website showed that I had a credit of {$5900.00}. I called BOA 's customer service line and was told by the BOA agent that I had authorized this second withdrawal, despite that I insisted that I had not and despite telling her that BOA had admitted having these same problems the previous month. I eventually was transferred again to BOA 's credit card fraud unit. I explained again that BOA had made a second unauthorized withdrawal from my checking account. The fraud agent insisted that I had authorized the transaction because her computer said I had. Please note that I called the day after this second unauthorized withdrawal was made. I am a XXXX XXXX, of sound mind, and would have known if I had made such a large payment on line the previous day. Furthermore, it is my practice to check my on-line account of each creditor to verify that the charges are correct and that I have not made previous payments. I also immediately record all payments from my checking account in my checkbook. No such duplicate payments appeared in my checkbook. 
The agent eventually agreed to return the {$6700.00} to my checking account but told me that it would take 2-7 business days. I demanded that she expedite the return of my money. Eventually she received her supervisor 's approval to do so, and told me that it would take no more than 3 business days to return the money. I am reporting this incident on the day of this last phone call and do not know if BOA will timely replace the money it fraudulently withdrew from my bank account. 
This computer glitch or business practice of automatically withdrawing a second amount from my bank account, and probably the bank accounts from other credit card holders is outrageous. I luckily had money in my checking account to cover this second withdrawal, but insufficient funds to cover the many other bills I must timely pay. Multiplied by the number of holders that may experiencing this problem, BOA is receiving the benefit of potentially tens of millions of dollars in interest free loans from its customers. 
This is a fraudulent and unfair business practice by Bank of America that must be stopped.