Re: HTC TP2 Cradle/Dock charging data kit
Nowhere in the listing does it say it's only compatible with GSM phones.
It's seller error, and you can do a chargeback (AMEX is great about this).
Contact your card issuer, and tell them you're willing to ship the item back, provided the seller pays for it. You already paid shipping to you, and since it's his error, he should pay shipping back to him.
Here's how it will end up: he'll refuse to pay for shipping, you'll keep the item, and he won't get paid.