Frozen my entire account after receiving a policy pay out

I'm appalled by FNB's actions. A few weeks ago, my brother-in-law lost his father and received a life insurance payout from Sanlam. However, as soon as the money was deposited, FNB froze his entire account, blocking his access to any of his funds. This occurred just when his debit orders were due, leading to bounced payments.

After everything he’s been through, he now has to deal with FNB just to restore his account. They didn't even reach out for confirmation or clarification before taking this step. They've also requested a multitude of documents that he now has to scramble to gather. I've never seen anything like this. How can funds from Sanlam be considered *****ulent? Its one thing to freeze the a policy amount but to freeze his entire account? This is utterly unacceptable.