I had the same sort of experience with ProActive acne treatment, a few years ago. Except, it was NOT a free sample. I ordered a kit of the various products (from their website), at the regular price. Then they sent me another, unsolicited kit the next month, with an invoice! When I called about it, they told me that, when ordering the first kit, I had agreed to a monthly subscription, simply by ordering the first one! Apparently, it was in tiny "mouseprint" writing, somewhere on the website. They did agree to take the kit back, pay the shipping, and cancel the "subscription". (By the way, the combination of ProActive solutions did work very well on my teenaged son's acne. But it was too expensive to keep buying every month.)

I had another such experience with "Hercules Hooks", one of those "as seen on t.v." products. The hooks are good, but they started sending them to me every month, and debiting my credit card! It took several calls and a threat of legal action to get them to stop.