Family name was Płoszaj...
There are 686 people with this name at nasza klasa.pl
The site has a forum so it might be worth leaving a message.
Keep in mind that most of the posters at nasza klasa are youngsters. There are some older folk too, who might be able to help.
A carefully worded message might gain results.
Problem: You will have to register first and it's all in Polish.
edit: I notice that the name Ploszaj gives many results at ancestry.com