Product: Credit card or prepaid card

In late XXXX or early XXXX I added an " American Express ( AmEx ) Offer '' to two of my AmEx credit card accounts, a Starwood ( SPG ) and a Platinum account. The offer was for a 10 % credit back on purchases up to {$1000.00}. 

This offer was used through a {$1000.00} purchase on XX/XX/XXXX on the Platinum card and the {$100.00} credit was issued two days later. 

On XX/XX/XXXX AmEx reversed the {$100.00} credit following an email indicating " Hello XXXX XXXX, We've charged your account for {$100.00} and we'd like to explain why. You already received a credit of {$100.00} for eligible purchases at XXXX, We offered you 10 % back as a statement credit each time you used your enrolled Business Card on eligible purchases at XXXX by XX/XX/XXXX, for up to {$100.00} in total statement credits per American Express Card Member. However, we discovered that you received more than the {$100.00} maximum credit across your Card ( s ). To correct this error, we will debit your account for any amount credited to you above the {$100.00} that you were eligible for. If you used multiple Card accounts, we may debit across each of your accounts to offset credits you received. '' This assertion is incorrect and not supported by the facts/charges on my accounts. Interactions with AmEx customer care have not resolved the issue. This feels like fraud and/or abuse on the part of AmEx. 

The terms of the AmEx offer are copied below here for reference : OFFER DETAILS Get 10 % back as a statement credit each time you use your enrolled Business Card on eligible purchases in-store at XXXX  or online at XXXX by XX/XX/XXXX. Limit {$100.00} in total statement credits. See terms and exclusions. 
TERMS Must first add offer to Card and then use same Card to redeem. Only U.S.-issued American Express Business Cards are eligible to enroll. Your enrollment of an eligible American Express Card for this offer extends only to that Card. Limit of {$100.00} in total statement credits per American Express Card Member. Offer valid in-store, via the XXXX mobile app and online at XXXX. Valid at participating locations in US. Not valid on purchases shipped outside of the US. Valid on US website only. Excludes XXXX, XXXX, XXXX XXXX XXXX, XXXX XXXX XXXX, XXXX XXXX XXXX, XXXX XXXX XXXX, XXXX XXXX XXXX, XXXX XXXX XXXX, Copy and Printing Services, XXXX XXXX and XXXX, XXXX XXXX XXXX, XXXX XXXX, XXXX XXXX XXXX, XXXX XXXX, XXXX XXXX XXXX, XXXX   XXXX, Catalog and XXXX XXXX. Not valid for gift cards in bulk purchases. Offer is non-transferable. Statement credit will appear on your billing statement within 90 days after XX/XX/XXXX, provided that American Express receives information from the merchant about your qualifying purchase. Note that American Express may not receive information about your qualifying purchase from merchant until all items from your qualifying purchase have been provided/shipped by merchant. 
Statement credit may be reversed if qualifying purchase is returned/cancelled. If American Express does not receive information that identifies your transaction as qualifying for the offer, you will not receive the statement credit. For example, your transaction will not qualify if it is not made directly with the mer chant. In addition, in most cases, you may not receive the statement credit if your transaction is made with an electronic wallet or through a third party or if the merchant uses a mobile or wireless card reader to process it. By adding an offer to a Card, you agree that American Express may send you communications about the offer. POID : XXXX