Product: Credit card or prepaid card

I mailed my payment of {$1200.00} to American Express on XX/XX/2023 and they have failed to apply the payment to my account. I also included instructions for the CFO to apply the principals balance to the principals account each cycle for set off. In addition, I provided my notarized Power of Attorney, granting me the capacity to act as the agent on behalf of the principals account. 
They did not honor my financial instrument/conditional payment, proceeded to request additional payments from me, and have taken the adverse action of pausing my spending. On XX/XX/2023 an American Express executive assistant, XXXX XXXX, responded to my original instructions reminding me that I am... bound by the Cardmember Agreement and must make all payments on time, and that they reserve the right to report the account delinquent to all credit reporting agencies. 
On XX/XX/2023, I mailed correspondence responding to XXXX correspondence. This acted as a First Notice of Dishonor and Opportunity to Cure by following my original instructions. Here are some of the points I addressed in my letter. Let the record show that American Express still has not granted any of the requests mentioned to cure this matter. 
Excerpt from XXXX XXXX letter to American Express : For starters, you stated in your correspondence, You are bound by the Cardmember Agreement and must make all payments on time. Per the Cardmember Agreement, To pay by a certain date means to send your payment so that we receive it and credit it to your Account by that date. Let the record show that I am in full compliance with the Cardmember Agreement, as I did send American Express my payment via mail utilizing a legal tender. It is now American Express that is in dishonor and breach of contract by not applying my payment. 
According to the How to make payments section of the Cardmember Agreement a single negotiable instrument clearable through the U.S. banking system is binding by and well within my rights of this contract. In addition it is also stated that, When making a payment by mail : write your Account number on your check or negotiable instrument and include the payment coupon. I would like to emphasize the phrase or negotiable instrument, as that is the tender I originally sent to American Express. Furthermore the Cardmember Agreement states, If your payment meets the above requirements, we will credit it to your Account as of the day we receive it, as long as we receive it by the time disclosed in your billing statement. I would like for American Express to provide a written explanation of the requirement that was unmet and interfered with applying my payment. 
With all of that being said, I am completely confused as to why your correspondence is informing me of the Cardmember Agreement, when I have done nothing outside of my rights of the agreement, nor did I inquire about the Cardmember Agreement. When it is in fact, American Express who has violated their own Cardmember Agreement. 
Fortunately, I am willing to give American Express the opportunity to cure this matter by following my original instructions both enclosed and outlined below. I would also like all negative remarks sent to any credit bureau/agency in regard to a late payment to be removed, as it is American Express who failed to apply my payment. 
This is my first attempt in notifying American Express that they are in dishonor of the instrument that I previously enclosed ( U.C.C. 3-503 Notice of Dishonor ) and requested to be returned if not accepted, which did not happen. This also acts as a U.C.C. 3-307 Notice of Breach of Fiduciary Duty. 

On XX/XX/2023, American Express had written correspondence informing me that they recently notified you that your APR for all transactions would increase to the penalty APR on XX/XX/2023. We apologize for any confusion this may have caused. The XXXX for Purchases on your account will remain Prime plus 20.74 %, currently 28.74 %... I believe this is one example of admission of guilt from American Express for failing to honor my conditional payment/financial instrument and follow the instructions. In addition, on XX/XX/2023, I received an email from American Express with a Notification of Credit Limit Increase. I believe this is another admission of guilt for dishonoring my conditional payment/financial instrument. If the claims made against me by XXXX and American Express are that I owe and have failed to make payment, there is not a logical reason for increasing my credit limit at this time, out of all times. American Express has only increased my credit limit once during the few years Ive been a cardholder. Both of these are poor attempts in trying to negotiate and/or offer me something in lieu of my original and lawful requests, which I will not accept. 

American Express is breaching their contract ( Federal Reserve Act Section 16 & USC ) as a FDIC member by not depositing my financial instrument.This has placed me in a compromising position of having to risk adverse action of late payments or suspension of service, if I do not abide by the payment option they prefer, which is completely unlawful and violates the following United States Codes : laws ( 12 C.F.R. 229.21 - Civil liability and U.C.C. 3-307,103, and 4-106 ).