STYLETHREAD -- LET'S TALK SHOP!

I've won two court cases several months ago and still haven't recieved any of my judgement. A few days ago I got a letter from a company telling me that they can help me recover the money that was awarded to me by the court. They tell me that their service will cost me nothing unless they are successful in collecting the money. So I was wondering if anybody knows anything about this and things like how much it would cost. A flat fee or a percentage and what I might expect to pay. I just want to make sure I'm not going to get ripped off! TIA!