If you need, go to: http://www.magicjack.com/6/index.asp, look to the bottom of the page and click on Customer Care. It will give you an option to ask a question or connect with a live agent. I have used this a few times, usually ends up being a simple fix.

By the way, you don’t need your computer turned on to receive calls, you can set MJ to forward to another phone if you are not online. Very convenient, unless I want the peace and quiet of phones not ringing!

I don’t understand all the negative comments. I have been using Magic Jack for three years now and very happily not paying the phone company, or Vonage for that matter.
You do need a high speed internet, maybe part of the problems? I have taken my computer on vacation, set it up with a portable house phone and, bingo, free phone calls from all over the country.
I also have a wonderful choice for local area codes and I know they are expanding all the time.
I also use it for my office line. Conferencing is easy and clear as a bell. They did have it down for a bit recently for upgrades, but I didn’t mind, they emailed me in advance to let me know it would be down. Hey, IT at my company pulls systems down all the time to update.
Anyway, sorry if you had a bad experience. I would recommend this to anyone. And no, I do not work for Magic Jack, just a very happy customer.