Nothing. It got privatized and is currently owned by Deutsche Bank.

Something must have gone wrong. I know for fact that in Poland you can bank at post office at least since 90s. Its still common think for seniors to have no bank account because there is no need to. They typically get pension in form of a government check that they cash at "Poczta Polska" and then use cash to shop. Post office also pays all the bills, utilities etc, so long as you know corporation/receipient bank number.

No, Post Bank was sold to Deutsche Bank. It was created by the Deutsche Post, who then spun it off, funneled a lot of their branches into it (so you have bank offices that also rent out a desk to the Post) and sold it to Deutsche Bank.