I, too, responded to a random email offer and ended up with a half-way decent necklace... and a "membership" I didn't know I had. Fast forward a few months, the site says I have $119.96 in "credits"... they're not "credits," that's just the amount you pulled off my credit card! LOL
I spoke to a customer rep & was told that I could not get a refund, but in the future I should be sure to opt out of my monthly payment by the 5th of each month.
Yea... avoid this shady set-up like the plague.