Hello,
i feel with you, but i dont understand how they could steal you the money. Do you mean you buyed, and left the bitcoins at your account?
How much time passed between your buy and their scam trick ?
from my expierience, avoid MT. Gox also.
greetings
Basically, he purchased bitcoin, they took his money, bitcoin increased in value dramatically, and they canceled his order. The gain in value of bitcoin between his purchase and the cancellation is lost to him. Presumably Coinbase actually did purchase the coins back when he placed the order and they had the cash, so they're probably making a lot of money refunding him and selling those coins to someone else today at a higher value.