First, regardless of who put it there, hosting malware is a VERY GOOD REASON for an account to be suspended. Second, the Terms of Service clearly state that backups are your responsibility, that even under the best of circumstances system-wide backups may not be available/reliable and will not be made available to suspended accounts, so you should have local copies of everything important anyway. (And developing in a production environment is just a silly thing to do in any case.)
There is a suspension appeal process (see the "sticky" above) you can use if you believe that you were unfairly suspended. In the case of obvious hacks, the questionable code still has to be quarantined (moved to an area that you can access via cPanel/FTP but that isn't accessible via public channels), and you would be given a limited amount of time to fix the problem. But if it's not an obvious hack (that is, it can't be determined that you didn't do it, or if you left a gaping hole in security you were previously warned about), your appeal may well be denied. x10Hosting can't afford to have its servers blacklisted, so it's more than just your account at stake.
