Citibank Credit Card Complaint

Citibank Credit card department,

Payoff process Florida

I have a credit card with Citi ( AT & T Universal card ) that has - balances with - interest rates on it. A standard purchase, which is 20-ish %, and then - smaller balances, which are 4.9 % and 3.9 % respectively, until paid in full. During an online chat last evening, I inquired how payments were being applied and was told that they were first applied to interest ( and any applicable late fees ), THEN to the balance with the SMALLEST interest rate, and then any additional ( above/beyond the minimum payment ) is applied to the balance with the highest interest rate. However, every place I look online, I read that payments must first be applied to the interest/fees, and then any remaining goes to the balance with the highest interest rate. That clearly is n't happening in this case.