Bank of America Credit Card Complaint

Bank of America Credit card department,

Credit determination Vermont

In - 2016 I received my statement from Bank of America with a balance of $48.00. I scheduled payment in time for the due date for the full amount as I always pay all my credit cards are paid in full monthly. By mistake I clicked on the wrong line on bill pay and sent the money somewhere else. I have proof of this. I then received a statement from Bank of America in - showing the amount was not paid. I immediately called Bank of America and explained. They told me that due to my excellent history there was no issue, all I had to do was pay the amount which I did. I received last week a notice from them saying my credit history was downgraded and my credit limit was reduced. I do n't care about the credit limit as I do not use this card very frequently but I am very angry at this action for no justifiable reason. I would like to have this corrected with the proper Credit Bureaus and cancel this credit card. Please advise how to proceed.