I know nothing about this case, but I have a few thoughts about this story.
1) The "full story" is actually rather sparse on exact details. The author quoted just a few words of "Your Projects are at risk of suspension", but doesn't provide more details about what was actually in the email. Did something else potentially cause this shutoff, not just billing? (I agree, based on his wording that this likely was a billing issue, but it would be good to know the full story).
2) The OP has not replied to any comments on here.
3) If the OP is reading this, they should go through their front-line support people at GCP saying this story is about you, so they can help you look into it. (it'll likely get the PR people to know who you are). If there was really a screw up where you paid and were still shut off for billing non-payment, I bet that would lead to a larger postmortem internally.