JPMorgan Chase & Co. Credit Card Complaint

JPMorgan Chase & Co. Credit card department,

Late fee Minnesota

I paid my Chase-Southwest Airlines credit card on time as always, arranged online through my bank. I apparently typed the amount off by $10.00. This resulted in a $ -+ finance charge for late payment. When I protested, they said this is a legitimate charge, as the late fee is on the full amount of the invoice, which was 0ver $2000.00. Is this allowed?