MP3Fiesta, website that used to provide cheap and legal mp3 music, seems to become AllOfMp3 follower. It all started with billing system blocking, so that users were not able to deposit money to refill their balances, although downloading was available. They still allow you to download songs, but it's impossible to refill your balance.
My suggestion is to make your balance there 0 by downloading everything you want, just not to loose it, when the service will become unavailable.
MP3Fiesta owners plan to rebrand the service, move to another domain and restart the service. It's good news, since I really liked MP3Fiesta and their prices were really nice! I wish them good luck in reincarnation!
Meanwhile, I suggest Soundike as one of the best mp3fiesta alternatives!
They give 2 free songs upon registration, really low prices, fast downloading, and no problems with refilling balance (you can use PayPal as well). Read more about Soundike.