More and more companies have zero meaningful support when things go sideways
I'm guessing one or more of your sites allowed user-uploads in some fashion or another and someone put a file that is hash-flagged in a serious manner
What I find hardest to understand is: if there’s an issue with a website, why shut down all of my sites?
So, when you do relaunch with another service provider, I recommend putting all user-uploads on a system that sanitizes/reviews the file before saving and therefore it would never allow a file in with a known hash flag.
The experience you're having is a reason to choose use a hosting provider that allows multiple user account per human/company. (Many providers have a very strict limit of one account per human/business and enforce sub-accounts.)
As you're seeing, an issue on one sub-account or site can sometimes bring down an entire account and all related sites.
Hope you are provided backups, they likely do have them, but you may need a lawyer to get more info and you'd need to get in touch before the typical backups get rolled over/deleted.