There are so many questions this leaves unanswered:
- Was this a one-off error in Cloudflare's processes? (These things happen on a big enough scale.)
- Were you violating a specific clause of Cloudflare's T&C? How clear was the clause? What did you do to fix this?
- Was the issue that Cloudflare estimated that you're not paying enough given the bandwidth you're consuming? Did you end up signing up for the Enterprise plan?
Transparency would benefit both Cloudflare (in not making people unnecessarily apprehensive about becoming/remaining a customer) and you (in demonstrating that you're handling this issue in a professional and responsible manner).
Sales over the phone (was fastest) told me that it's good I contacted as otherwise in 24hours my account would be fully banned(whatever it means) and that they will prepare me an offer in 15 minutes, but it was taking longer (no response after an hour or so) and in the meanwhile I wrote Twitter and HN post which CTO of Cloudflare noticed and then after a while I've got another phone call from sales that I should update my ticket to ask unbanning my account as it was approved now by CTO which I did and that solved the issue at least for now - and that's it - no further info what the issue was, still waiting on Enterprise plan quote for me.
I don't know if this is the case for CF but it seems to be for other businesses.
I don't think it's usually that they don't know what's going on, but that they don't want to tell you, because they think that's giving away too many details.
I've been flagged in many systems as I move around in the world quite a bit, so sometimes I use a credit card acquired in one country in another, and a couple of days later using it on the other side of the planet, which triggers their anti-fraud systems. Then I write to them and they reply something like "Unfortunately you cannot continue to use our services as your account been flagged as potential fraudulent use. We cannot give you any details because then it'll be easier for fraudulent actors to work around it, so I'm sorry we cannot tell you anything else. Bye."