Sadly, as of 2020 I cannot seem to find any reliable resellers here in Europe for parts.
I think Zeusbtc have a branch in Poland, not sure if it's just a workshop where they only repair your miners or they actually do sell stuff, it might be worth looking into it, perhaps you or mikxxy should get in touch with them, if you don't get an answer I'll reach out to someone from Zeusbtc.
I'd wager that it's only repair shop in Poland, as their website sells everything over WhatsApp orders and they seem to have their warehouse in China (Hong Kong?). If you have someone from Poland branch, feel free to give me his contact or ask him if they have any warehouses in Europe.
Otherwise, I will try to contact their support to see if I can get in contact with someone from Poland.