Bank of America Credit Card Complaint

Bank of America Credit card department,

Transaction issue California

The bank of america applied my lump-sum payment to the lowest interested balance rather than paying the highest one. Is n't that a law that credit card co. has to pay highest interest first? I had - balances that the promotional rate will be ending at same date on -/-/2016 On -/-/2016, I paid $4000.00 toward ( I thought, ) soon will go up to 15.24 % ( balance $4000.00 ) But BA applied it to the another balance that would go up to 7.49 % ( balance was $5100.00 ) * And the balance of 15.24 % of $4.00 ( - 2016 ) was increased to - ( - 2016 ). $5.00 more without the cause! Why? Reps could not explain to me about all these.