Complaint Review: MAGICJACK

I signed-up for Magic Jack Plus's 30-day money back guarantee on the internet which totaled $81.64 which I paid for using my Visa debit card. I did not like Magic Jack Plus, it was NOT compatible to my computer, so I returned their Product within the allotted 30-day trial period (it was within seven days actually). I also got an U.S. Postal Service Delivery Confirmation receipt and it has been confirmed that it was delivered back to them on 12/22/2011. I have contacted them twice and both times they have told me I should receive a credit to my card within five days. And have yet to see the credit. The 1-800 number I called the first few time is now no longer a good number. And the ones on the Internet are wrong also. Magic Jack is currently doing business on a global basis and they advertise their product almost everywhere one looks so hopefully they might be persuaded to do honest business because of their high visibility? If Magic Jack refuses to return my payments how might I file a more serious complaint?  This can't even be legal!!