According to the current anti-money laundering and tax administration legislation and the overall know-your-customer principle, banks find it essential to maintain an overview of their customer base. This applies to you too, despite that your account(s) have already been closed. That is why we are periodically seeking further information on your personal data, economic activities and individuals related to you.
As long as you have a valid credit agreement, you are obliged to submit the required information to the Bank.
You can learn more about the "Know your customer" (KYC) questionnaires here.