Privatisation of Polish banks (and other industries) between 1989-2015 is a long story of corruption, bribery and ouright theft (that even the native Polish population is not fully aware of!!
Don't try and change the topic - you claimed 1989-1995, not 1989-2015.
2. BPH and Pekao SA were sold for about 5-6 billion zlotys (each of these banks has currently assets of about 115 billion PLN or more)
Given that Pekao has expanded massively since 1999 (it used to have the monopoly on foreign transactions, which was then taken away in the 90's and it was a shell of its former self, combined with some small retail operations) - basic economics should tell you that it's obvious why it's worth much more now. Unicredit invested a considerable amount into the bank, and as a foreign-owned bank, it was often the first choice for foreign commercial clients as it knew what it was doing. Don't try and make out as if it was an incredibly wealthy bank that was privatised for peanuts - it's simply not true.
I've found the figures for 1999. Pekao SA turned over about 5.3 billion złoty that year and made a profit of around 136 million. So - if your figure of 5-6 billion złoty is right, then the government made a decent deal there. Furthermore, shares were on sale then for 49zł. These days, they're worth about 142zł. It's not exactly a huge increase compared to the rise in value of other assets.
I'm not familiar with BPH so I won't comment there.
4. almost 50% of shares of PKO BP were sold for about 7 billion PLN (basically for peanuts)
Anyone that's familiar with Polish banking history knows that PKO BP was in a terrible mess in the 1990's. If it wasn't for the fact that it was too big to fall, it would've fallen - it's only in the last 10 years that it really started to become the dominant retail bank. One huge problem that PKO BP had (and possibly still has, I'm not sure) is that they had a ridiculous amount of bad loans.
3. bank Handlowy, Big bank Gdanski, Polski Bank Rozwoju i Polski Bank inwestycyjny were also sold.
As they should have been. It was vital to create some genuine competition in the banking market and allow privatised banks to consolidate with other privately owned banks. We're seeing the end game now, but for a long time, Poland had far, far too many banks. Even today, the problems caused by small banks (such as with the blatantly corrupt SKOKi) can really hurt the government financially.
so, according to very modest assessment, Polish citizens lost about 200 billion zlotys as a result of this scam called "privatisation of banks"
Your assessment is based on those banks hypothetically performing as well as they have under state ownership. It's nonsense.
Thats about 80% of Polands GDP at the time. I never heard of the concept of communist countries with successful banks, especially bankrupt countries with hyper inflation.
As far as I know, there weren't many successful banks in Poland in the 1990's. WBK and Bank Sląśki come to mind, but most of them were just small regional banks.