If that’s the way your email program works, it’s working exactly as it should.
That’s one definition of what it means to block email. That may be exactly what “blocking email” means to your email program: “When email from this sender arrives, put it in the junk folder.” You said the email is coming “repeatedly to my junk email box”. It promises to prevent email from a specific sender from reaching you, but if the sender determined, the block is easily bypassed. And spammers are determined … boy, are they determined! Blocking senders is useless in the war against spam. Blocking email by the “From:” address is seriously overrated it’s effectively useless.