Product: Credit card or prepaid card

American Express has inappropriately mishandled numerous charges and credits on two of my accounts. One account is enrolled in Pay Over Time, " POT '' and the other card I had setup a " Plan It '' for one single charge. 

POT Problem : American Express and their customers and representatives have failed to resolve my dispute with them since XX/XX/XXXX. I made a few charges that had been applied to my Pay in Full portion of my account and when I returned the items contained in those charges, they inappropriately credited my POT portion of the account for those items returned that were charged to my Pay In Full portion. After speaking to 20+ representatives trying to resolve about 3-4 charge/credits ; somehow, and without my consent or knowledge, they moved numerous charges and credits ( including ones I was not even inquiring about ) from my Pay In Full to my Pay Over Time portion, applied payments to POT rather than my PIF balance, completely mishandled and illegally moved charges and credits that I since XX/XX/XXXX, I can not tell what is an original charge/credit, what portion balance the charge/credit appears in, and have no clue what some of the changes they've made to these charges/credits are for or if they have incorrectly added charges while trying to resolve a simple dispute/inquiry. I have submitted my claim/complaint to their legal department and have not heard back from them which my certified return receipt shows they received my complaint and request for arbitration ( per their contract ) inXX/XX/XXXX. In XX/XX/XXXX, a representative FINALLY got back to me but he is not in their legal department and is in their account review department and responded to my 2nd or 3rd request for them to completely review my account and to provide me with a detailed list explaining what charges/credits they moved, why they moved them, what charges are currently on my POT portion that I am incurring interest for and to date, he has yet been able to rectify or even understand himself, why these representatives moved these charges and credits and where they originated from. Amex has yet to close my accounts and reverse the membership yearly charge which I am entitled to since my request was made within the 30 day period ( per their contract ) which I requested in several letters to them including the claim/notice letter I sent in XX/XX/XXXX. This account is a complete mess and even Amex has admitted that they can not figure out what the representatives did or why they inappropriately moved around charges and credits that should have just cancelled each other out since they charges and credits were for same transactions. 

Regarding the other account - " Plan It '' Again, I made a purchase and setup a " plan it '' with Amex that included three monthly payments for my total charge. I returned 75 % of the items in that charge which resulted in a credit to my account ; however, Amex did not apply that credit towards the original transaction and again, inappropriately and illegally applied that credit to a different balance on my card. 

In summary, XXXX has and continues to illegally and inappropriately apply credits of returned merchandise to incorrect balances and NOT to the original charge transaction which causes the person, like myself, to be paying interest on charges that have since been returned and should have, in so many word, cancelled each other out. XXXX should not be allowed to continue to operate like this as this violates so many laws and being a paralegal myself, I have tried resolving this with XXXX reps, agents, legal and to date, it has been 6 months and not only has it not been resolved, they continue to move more charges and credits around and I can not make any sense out of my statements, charges, credits, amount due anymore and need assistance with this.