Citibank Credit Card Complaint

Citibank Credit card department,

Late fee Louisiana

This is the second time this has happened to me. I received my monthly statement from home depot which has a due date on the - day of the next month. I usually pay at the local store on or before the - of the month, However, i paid by us mail on -/-/2017 for the due date of -/-/2017, total bill of $27.00. On -/-/2017 I received a notice that my account had been assessed a $26.00. late fee plus $1.00. interest. The $27.00 was posted -/-/2017. 10 days from - - to - - - - did better. . interest on what???