Yeah, I've been extremely disappointed with disputes on Amex Platinum.

I literally had a bike rental company in Amsterdam attempt to get me to conspire to report a bike stolen (which had briefly been stolen but was back in my possession), and then when I refused, charged me as if the bike had been stolen!

I reported all this to Amex, and I was never refunded, and to my knowledge, the attempt fraud was never investigated.

Seems the common thing between the three of us not getting chargebacks handled right is that the merchant was outside the US.