Product: Credit card

I have a CapitalOne " World '' Mastercard, which has a cashback bonus program. I always pay the balance in full each month by using CapitalOne 's website to schedule a withdrawal from my checking account, to occur on the due date. To make my most recent payment, I redeemed most of my accumulated cashback bonus for an account credit, and ( as I normally do ) used CapitalOne 's website to schedule a withdrawal from my checking account, setting the amount to the difference between the balance due and the cashback credit amount. After the due date, I got an email from CapitalOne saying they were charging me roughly {$10.00} in interest. I called them to find out why, and the representative told me that CapitalOne does not count credits ( including both cashback bonus amounts and refunds from merchants ) as " payments '', and so they do n't reduce the amount you owe for a prior statement period. Instead, CapitalOne nets such " credits '' against the purchases you make during the statement period in which they occur, reducing the amount that you will owe on the *next* statement. This delay in accounting for credits seems to me to be unfair, illogical, and not in keeping with how such transactions are treated by other providers in the industry. Certainly, it is not how cashback bonus redemptions or refunds are treated in my XXXX and XXXX XXXX XXXX credit card accounts. I always pay the balance on those cards in full each month, and whenever I have a cashback bonus redemption or other credit to my account, I reduce my payment accordingly. I have been doing this for over a decade, and XXXX and XXXX XXXX XXXX treat those " credits '' just like any other payment. 
Further problematic, to my mind, is that CapitalOne 's treatment of credits is conditional on subsequent transactions. This seems even more unjustifiable. Specifically, if, after a statement period ends, your subsequent " credit '' transactions exceed subsequent purchases, then ( and only then ) the amount you need to pay to avoid finance charges is reduced by the difference. So for example, let 's say your statement for XXXX XXXX - XXXX XXXX shows a balance due of {$1000.00}, with payment due on XXXX XXXX. Then, on XXXX XXXX, you get a refund of {$300.00} ( say, because you returned an item you purchased in XX/XX/XXXX ). Under CapitalOne 's policy, that {$300.00} does not *necessarily* reduce the amount you need to pay by XXXX XXXX to avoid finance charges. If you charge nothing during XX/XX/XXXX, then you need only pay {$700.00}. But if you charge {$300.00} or more, you have to send CapitalOne {$1000.00} by XXXX XXXX. I can see no legitimate justification for this inconsistent treatment of the credit transaction. Either CapitalOne got that {$300.00} before the due date, or it did not. Its inconsistent treatment of the credit seems like an attempt to hide an improper policy from scrutiny by tempering its most egregious effects. 
A further ridiculous consequence of this policy : a direct redemption of a cashback bonus for statement credit is not a " payment '', but if the cashback bonus is credited to my bank account, and I then send the money right back to CapitalOne, it is. 
CapitalOne 's odd practice is a trap for the unwary. At the very least, it should disclose the practice clearly, unambiguously, and prominently, in a location and context that ensures consumers will understand and be able to account for it.