Bank account blocked

Title
Why was my Commerzbank account blocked without warning?
Why was my Deutsche bank account blocked without warning?
Why was my Postbank account blocked without warning?
Why was my Sparkasse account blocked without warning?
Why was my BNP Paribas Bank account blocked without warning?
Why was my Crédit Agricole Bank account blocked without warning?
Why was my Société Générale Bank account blocked without warning?
Why was my Barclays Bank account frozen without warning?
Why was my HSBC UK Bank account frozen without warning?
Why was my Lloyds Bank account blocked without warning?
Why was my Nationwide Building Society account frozen without warning?
Why was my NatWest Bank account frozen without warning?
Warum wurde mein NatWest Bankkonto ohne Vorwarnung gesperrt?