Annabel, sorry to say it but you've been scammed.

FW's free, just like basic LW. The official site for downloading LW is www.limewire.com
The official site for downloading FW is http://www.frostwire.com

You should contact your bank/CC company & report this straight away. If the scammers have already overcharged you, there's a chance that they could keep deducting payments. Your bank or CC company will be able to tell you whether you should cancel your card.

If you paid for FrostWire you have been scammed, FrostWire is free
Check the 2 links below for more info. Page 5 of the first thread has a list of scam sites.
Membership? - **BEWARE** - Download p2p Clients ONLY Thru Official Sites (click on link)

get your $$$ BACK!!! (music members)

If I were you, I'd get rid of the version you have now...for all you know it could have spyware or adware included. Rather than keeping a scam version, download a clean version of whichever program you want from the official site only