Product: Credit card

I have had my XXXX point American Express Platinum Membership Rewards bonus removed from Membership Rewards account despite the fact that I have met all the terms and conditions of the credit card sign-up bonus. American Express claims that this is because I made a purchase at giftcards.com and that purchases of prepaid cards do not count toward minimum spend. However, even after subtracting the money that I spent on the prepaid gift cards, my remaining spend on the card exceeds the required {$3000.00} minimum spend within the first 3 months. 
In Summary : I applied for and was approved for an American Express Platinum personal card on XXXX XXXX, 2016. The offer terms were : 1 ) Spend {$3000.00} on the card in 3 months 2 ) Pay a {$450.00} Annual Fee 3 ) Receive XXXX Membership Rewards Points 6-8 weeks after minimum spend was met. 
-Between the dates of XX/XX/XXXX-XX/XX/XXXX ( 3 months ) I have spent {$6100.00} on this card. 
-American Express has informed me that my purchase at giftcards.com of {$2500.00} does not count towards my minimum spend of {$3000.00} and that therefore they removed the XXXX Membership bonus awards that they originally awarded on XXXX XXXX. 
-Even after subtracting the {$2500.00} and the {$450.00} annual fee that I have paid from the calculation, my remaining spend within the first three months still totals {$3200.00}, which is in excess of the required {$3000.00} spend. 
-American Express has explained to me that they ( erroneously ) applied the {$2500.00} giftcards.com charge to my " threshold '' {$3000.00} initial spend and that because of this they first incorrectly awarded me a XXXX point bonus and, after the 3-month minimum spend period was over, they removed the bonus and will be unable to reinstate it at a later date. 
-Multiple representatives at American Express have told me that I did not meet the {$3000.00} minimum spend within 3 months, despite that fact that it is easily verifiable that I have, in fact, met the minimum spend. 
-It states clearly in the application terms and conditions that I received when I applied that prepaid cards or cash equivalents do not count towards the " threshold '' or minimum spend for a credit card bonus. 
-I had no control over the fact that American Express incorrectly applied this giftcards.com purchase towards my threshold spend. 
-The terms & conditions on my application do not prohibit the purchase of gift cards. In fact, each of the ( many ) times that I have waited on hold on the phone for American Express Platinum card customer service representatives I have been subjected to lengthy advertisements for buying American Express cash equivalent gift cards! Given this fact, a reasonable person would presume that American Express encourages its customers to buy these type of gift cards. 
My spend on the card was as follows : Statement ending XXXX/XXXX/16 : {$3100.00} Statement ending XXXX/XXXX/16 {$370.00} ( Partial ) statement ending XXXX XXXX : {$2600.00} = {$6100.00} total within 3 months I respectfully request that American Express reinstate my XXXX point bonus. The terms and conditions of the agreement stipulated that the bonus would post 6-8 weeks after the minimum spend is met, so I would expect the bonus to post 6-8 weeks from XXXX XXXX.