Don't get me wrong, I fully understand that a fascist is not the same thing as a communist. But they're equally despicable.
Fascism is inherently anti-democratic, communism isn't. I know communism is a shorthand for stalinism, maoism and other totalitarian ideologies that use socialist facade (similar to national socialism) but it's worth to make an effort not to discredit the whole idea.
Also worth pointing out: referendum campaign has less strict spending limits compared to parliamentary elections so this is one more way (on top of utilizing state media and state owned enterprises) that PiS can outspend competition in upcoming elections which are held on the same day.