I have a citibank credit card. On my XX/XX/XXXX billing statement, I made a payment of {$1600.00} on XX/XX/XXXX for a balance of {$2600.00}. The remaining balance was {$1000.00}. The payment due date for this statement was XX/XX/XXXX. I realized that the remaining balance was still not paid and paid the remaining balance on XX/XX/XXXX. My billing statement for the next month reflected both payments and an interest charge of {$20.00}, and no carried balance. The balance was paid in full by the time the billing statement arrived. I paid the full balance of new purchases this billing statement, and the {$20.00} interest fee and carried no balance. On the next month 's billing statement, I received an additional {$14.00}. The bank claims this was residual interest, but I did not carry a balance, and the only balance I did carry was {$1000.00} from XX/XX/XXXX and the date I made a payment on XXXX. 
