Hey buddy, I hope it's not too late as I just saw this topic.
I am from Poland and I'm pretty experienced in evading the restrictions.
Here are some legit casinos in which I've never encountered any problems with withdrawals:
A tip: sometimes the Finance Ministry blocks the domains of certain casinos and they immediately register another domain containing a number after original name. For example: www.betsafe.com is not accessible in PL so they created www.betsafe1.com and so on. Now we're at www.betsafe55.com
betsafe55.com
alfcasino (dont know the number)
cadoola casino
kingbilly
spinia
wildblaster
energycasino
mrbit
gunsbetcasino (check if it's legit - I only know it's accessible)
evobet
playamo
bitstarz
BTW. Ground casinos suck here, don't even bother. Cheers