Amex Credit Card Complaint

Amex Credit card department,

Credit determination California

I checked my credit score on - and it says that for my American Express credit card I have missed 12 payments, witch I 've never missed one. The card it 's closed already because on - - I made my last payment.. I had a balance of almost $5000.00 in - -, could n't pay it off like they asked me to, so I call American Express and made a payment plan with them for 12 months of $380.00 a month. I never missed a payment for this card and it shows on my credit repost that I missed all the 12 months payments.. I can prove that I never missed a payment because they discount automatically from my bank account every month. I open a dispute on - to verify that, but nothing happen.. My credit still bad because of that..