I've had a run in with these folks before and it took some time to straighten it out. They were handling billing for a service I did purchase with a one time payment. All well and good, but they then used my credit card info to start a monthly membership charge to their service, which I subsequently managed to cancel.
Since then I have checked to make sure they aren't on any billing service lists, if they are I simply don't deal.
But now, more than a year down the road, I find that they're charging me a monthly fee again, and I can't immagine what for. I will be looking into it though, and I'm phoning the credit company tonight to stop any further payments to them. They're pure slime.