USAA Savings Credit Card Complaint

USAA Savings Credit card department,

Payoff process South Carolina

USAA offered a promotional balance transfer for 0 % for 12 months with - transfer fee. The problems come with the way they are applying my payments. They are applying my payments only to previous statement charges. I made payments for new charges, but they applied them to my 0 % balance transfer balance from my previous statement instead of applying it to new purchases that were accruing interest, lowering my 0 % balance. Is this legal?