Hi Martin,
I would be careful with letting just anyone clean your sites. Hopefully you gave them their own log in and they are doing manual clean up not using an automated tool (they don't always find the malware and completely remove it). Just something to watch for. I manage WP Security Lock (Regina is a member here), $5 a site is LOW so it just makes me wonder and I don't recommend Host Gator for that many domains. You want each site on a separate cPanel not a shared. One gets hacked they all do.

We charge $497 a site to manually clean and then our most popular package is $247 a month per site to manage. Hopefully you get all your sites cleaned and moved to their own cpanel so this doesn't happen again. Wordfence is a good plugin but I recommend iThemes Security Pro and BackupBuddy.