Product: Credit card or prepaid card

In XX/XX/XXXX, American Express offered me a promotion of 6.99 % on all for purchases. Before I jumped at the offer, I wanted to make sure that I understood the offer ( I thought it was too good to be true ). I chatted with an American Express representative to ensure the rate, the duration & the terms. He confirmed that ALL purchases made between XX/XX/XXXX-XX/XX/XXXX will have an interest rate of 6.99 % There fore, I decided to pay the entire balance & increase my credit limit to be able to charge our whole XXXX vacation on the card. Our vacation was in XX/XX/XXXX, we maxed out the card because of the promotion. In XXXX ( or XXXX ) I looked at my credit card statement only to find that I was charged the full APR ( 24.99 % ). I called AMEX & they advised me that only airline purchases would qualify under that promotion. I was appalled, I explained that I chatted with a rep to make sure before I maxed my card. They said that they will investigate ( pull up the chat & get back to me ). After no response, I called back a couple weeks later. I spoke to a different rep & was told that they found the chat & I was indeed promised 6.99 % on ALL purchases ( not just airline charges ). So I was credited two months worth of interest & was told to call back every month to get a waiver, as they couldnt make the correction to automatically charge the 6.99 % for future statements. 
I called a few months later ( as instructed ) to get my interest adjustments, but was told that they could not credit me, they would have to research this yet again. I spoke to several reps & supervisors, they advised me to give them time to research & call back. A few more months past & no response from AMEX. When I called back, they acted as if they didnt know what I was talking about. This run around happened for a whole year. I took down names, but I cant find my notes anywhere. Ive spoken to numerous reps and supervisors. Finally, I spoke to supervisors named XXXX & XXXX ( XXXX? ) I explained my situation again & they both said that they would have to research & try to pull up the chat from XX/XX/XXXX & they asked me to call back. I called back on XX/XX/XXXX & spoke to a frontline rep. He advised me that AMEX found the chat & will honor the reversal of intest, but he had to forward a request to expedite/complete. He asked me to call back on Friday XXXX, to check on the status. When I called on XXXX, I was told that the escalation team is honoring the credit, they just had to calculate the difference between 24.99 % ( what I was charged ) & 6.99 % ( what it should have been ). So if I dont see a credit by next Friday, to call back. Today XX/XX/XXXX, no credit, so I call. The frontline reps tells me that my case is closed, as I received two credits already. At this point I ask for a supervisor, I get XXXX. - XXXX. advises me that they cant find the initial chat promising me the 6.99 % and the only thing they could do for my troubles is credit my account {$250.00}. This is unacceptable to me, because I know they have to have record of the chat. They found it before. They also had conveniently lost notes about my previous conversations with other reps & supervisors. A {$250.00} credit doesnt even come close to making this right, so Im asking for your help. XXXX XXXX