Hi
Since poland is now part of the EU, I don't think you would need a visa. The Germans for sure do not need one, but we need one for their bloody country. Is that fair or what?
Email
passport@mweb.com.na and ask them. They area a passport agency in Windhoek, the capital of Namibia, and would probably be able to answer your question.
Otherwise, email the ministry of home affairs, try
sgoagoseb@mha.gov.na or
tmushelenga@mha.gov.na
Hope you visit Namibia one day.