Citibank Bank Account Or Service Complaint

Citibank Bank account or service department,

Checking account Deposits and withdrawals California

I have a Citibank account. I paid my Best Buy Account of $58.00. Today, Best Buy, which is part of Citibank, went into my account and took $250.00 without my authorization. I have been making regular payments on this account, and today they decide to take an additional $250.00. Citibank said there is nothing they can do and Best Buy is saying the same. What rights do we have when it comes to our bank accounts? How can I get my money back?