Problems with being blocked from joining Facebook groups

I am having problems joining and posting to groups on Facebook . I was blocked from joining for 30 days and it has been more than a month and I am still unable to join groups or post. Why is this? I thought I should have been unblocked by now. Also, when I log in I keep getting asked to verify my identity and when I do this it says you are blocked from joining and posting to groups for 30 days because you did not pass a security check. I know I did. So whats wrong?