Originally Posted by arg

There are a few ways, but the most direct way is to contact the two registrars involved and see if they can just work it out nicely. If not, you find a registrar (typically the one you were using, but any registrar works) who will file for proceedings using ICANN's Transfer Dispute Resolution Policy. But no registrar is obliged to do this, and they can charge whatever they want to do it, so you've either got to hope for a favor or prepare to get screwed even more. If the registrar you were initially using is partly to blame for the disputed transfer, they'll probably be more inclined to help you out...no registrar wants bad PR of people saying they screwed up and wouldn't help to correct the problem. If you can't get a registrar to help you, civil court proceedings would be a logical next step, but I doubt that's even been done since ICANN's latest policies were enacted...I think most fraudulant hijackings are corrected just informally between registrars.