I mistakenly underpaid my XXXX credit card balance to Bank of American by {$10.00}. The amount due was {$730.00} and I paid {$720.00}. As a result, interest was charged to my account the following month. However, that particular month I had an unusually high bill because I had gone on vacation : total new charges were {$5300.00}. Nevertheless, the bank charged me interest on that amount in addition to the unpaid {$10.00} balance. This was keeping in line with their policy of charging interest on newly accrued charges if the previous month 's balance was not paid off in full. As a result, {$39.00} in interest was charged to my account. I did not notice the charge until the following month. Even though I paid the {$5300.00}, the following month I was charged {$44.00} in interest because of the {$10.00} balance which I had not noticed. After calling the bank to explain the situation, they agreed to refund the second interest charge " as a courtesy '' but not the first. I do question the ethics of having a rule that allows interest to be charged on newly accrued balances regardless of the past amount due. I have a history of always paying off my credit card balances in full and have always been a good customer. This however, did not sway the bank whose customer service representative stated to me that she thought their offer was " more than fair. '' I disagree. To have to pay {$39.00} in interest on an unpaid {$10.00} balance when I have been an outstanding customer for many years seems unreasonable and I would like this amount refunded. 
