Ask HN: Why do my online accounts keep getting banned?
Fidelity is the one to focus on immediately because it's the most serious-- by far-- and they have walk-in locations where a real account rep can help you. The downtown SF location near Market & 2nd has excellent staff in my experience.Fidelity might turn up something about identity theft, or credit reports, or red flags, or similar. If so, you can handle these. If not, then ask a private investigator for help; a good PI has research tools to find problems then help you fix them.