Wippy.com/za Deceiving internet advert Internet

On 5 Apr 2013 an advert appeared on Facebook as many others, advertising free products to be claimed.  I clicked on the ad and landed on a web requesting registration before you can enter their web.  On doing so, it said that the email I provided was already in use, so I used my secondary email.
 
I was now on Wippy.com's auction page and saw all their good offers.  I made a bid on an iPod shuffle for R57.17 and paid for it with my cr card.  On 16 April I received an sms from my bank regarding a purchase from Ask-Wippy.com of R469.23.

I then remembered seeing something on my receipt about a 7 day free trial of membership, but was under the impression that I did not sign up for this membership, I only did the one bid, finish.  I immediately send them an email about the money taken from my credit card without permission and that I do not want membership.

Up to now I have been to and thro with Wippy regarding this matter.  I had to send them screen shots of my bank account to prove that this money was taken from my account.

Today I received a final reply that when I did the bid on the iPod, I was automatically signed up for membership and they cannot refund me, but membership will be cancelled without further montly fees .

Please tell me if there is anything else I can do to stop these people, because I'm sure that I am not the first person to be ripped off like this with misleading ads and luring you into unwanted membership just because you bought one article.