Citibank Credit Card Complaint

Citibank Credit card department,

Delinquent account Delaware

I purchased two dresses from Macy 's totaling $260.00. Bill was due -/-/2017. I returned both dresses on -/-/- for full credit which - out the balance - and with enough time to be reflected on my next bill. But, when the next bill came in there was a Late Fee of $27.00 and a Delinquent account status even though the bill clearly shows full credit of the previous month 's balance. There were NO interest charges -which means their system knows it was paid in full - but still applies a late charge and delinquency. Nothing was owed - the full balance from the previous month was - out. I called and they told me I had to pay even though the full credit covered the balance. I advised the agent that paying would have caused a credit balance of $260.00 and she said no it would n't??!! Then they told me I had to pay the new charge made on -/-/- of $37.00 to remove the late fee and delinquency even though it is not due until -/-/-. I asked for a supervisor who told me the same thing and stuck to the same story??!! Then I tried to use their online system which is so horrible to use - the chat function does not work - the email system provided an auto response with no information on when they would get back to me. They are ruining my perfect credit score and trying to make me pay the $27.00 late fee. Please help. This is a scam - who pays when there is NO balance? How many others have they charged a late fee to when no balance was due? The fact that no interest charges were applied shows that this system is flawed.