Amex Credit Card Complaint

Amex Credit card department,

Payoff process Oklahoma

The conversation I had with the American Express credit card company was confusing as far as the exact numbers go, so the numbers I 'm using will not be exact but the way the CC company handled it should be obvious. I had a balance due in -. I paid part of the balance ( more than the minimum ). I made a purchase of $3000.00 in -. In - I paid $3100.00 on a balance of $3100.00 making my balance due of $15.00. My statement for the amount due in - showed an interest charge of $28.00. It looked odd to me that $28.00 would be charged on a $15.00 balance. I called the company. They told me that it is a trailing interest '' charge. Because there was a balance from the previous month ( I 'm thinking the $15.00 ) that, even though I paid them $3100.00 they were going to charge me interest on the $3100.00. In other words they are charging me interest on money that I have already paid. I asked the lady from the CC company if that was accurate and she said, yes, because the previous month 's balance was not paid in full they would use their '' trailing interest '' policy to charge me interest on money I had already paid them. Is it legal for them to do this? To my knowledge, none of the other CC companies I deal with operate in this manner.