I am quoting from this:
If you really, really think the question ban is an error, then email the team directly at the address provided at the bottom of every page. But note that Stack Overflow alone gets more than 3,000 questions per day, so reactivation of banned accounts is not a high priority.
As the system may be wrong about banning/blocking user, it would be a positive step to make a special email for these kind of users, to inquire about their situation, and reactivate/unblock them immediately if the system got it wrong. You may say there is already email@example.com, I am with you in this, except they don't give a priority to such kinds of messages, as they state in the wiki.