[support] My Drupal 7.15 just hacked :(

Hi, My development website (Drupal 7.15) setup 2 weeks ago. Only View and Chaos Tools Suite Modules installed. I contacted hosting company and they said it's compromised through FTP -what I don't believe (if it's truth I'm really screwed because there is tons of other sites too :( ) I got "Security update" message but, since it's development website, I wasn't rushin' What's chances it's really FTP or something else? No other problems but "new" index page. Though, they could "planted" something? Suggestions? Thanks for any help, LAMP