Suspending & Unsuspending an user can be trivial with inbuilt functions (Notice that as of writing this, these are still experimental scripts). This is achieved by disabling password and changing www folder so that there's no access. Disabling password & login disables FTP, SFTP, SSH access, and renaming www folder disables HTTP access.
cd /scripts ./suspend.php USERNAME
cd /scripts ./unsuspend.php USERNAME