blizzard playing us fool - trial account

i got my trial account and played the game for 5 days, got to lvl 20 and yesterday i tried to upgrade my trial account, tried first with a visa card, keep saying was a invalid credit card number, ok so maybe its something with my credit card, so i tried with mastercard, same problem, 2 minutes later the bank called me saying that blizzard charged me u$19.99 , funny huh? they charged me with something im not even using , IM STILL ON A FREAKIN TRIAL ACCOUNT, i really hope someone can explain this to me and solve my problem, either giving me my full account or my money back, i already sended a message to billing@blizzard.com but no response yet, pretty fast their customer support huh?

P.S , NO, theres no problem with my bank and anything relative with blizzard