Erm that's exactly how they operate, they don't give credit.
Yes they do misrepresent themselves in TV commercials as offering credit to those with, erm, a blemished credit history.
However the way it works is you send them money until you've paid for the item, then they send you the item. After you receive whatever it was you paid for, you then pay for it again several times over. This gives the illusion of pre-payment and credit.
The problem is that most people with shit credit don't finish paying for the item they want, in much the same way they miss payments on real credit such as loans.
So if they fail to pre-purchase whatever it is they're buying, they end up with nothing. Now you have a problem, because the money they've already sent is not returned, at least not immediately and not without penalty.
The basic concept behind this isn't that bad, an acceptable version is called Layaway in the US. The way that works is you pick the item you want in the store, and they hold it for you for an agreed period of time. You make your payments, and if you manage to reach the purchase price prior to the time limit (usually about 3 months) you get to keep it. If you fail to make the payments in time, you get your money back. You can cancel the layaway at any time, and most businesses that still offer this service don't penalize you in any way.
Unfortunately that isn't particularly profitable. Often expensive and highly desirable items that would have sold earlier are left in storage and are never paid for. Sure they get returned to the shop floor eventually, but prices change and often businesses end up losing money if they offer this service. Which is why most no longer do.
However what Blue Hippo does is take this one step further. They worked out that by making the customer pay several times the normal value of the item, this can be profitable. Especially if most of the people they deal with have a bad history of making credit payments.