Spam Emails from Prezi - How to unsubscribe?

I keep getting almost-daily emails from Prezi. At the bottom, there is an unsubscribe link, "privacy@prezi.com." I have clicked this linked email address and sent an email requesting to unsubscribe. In response, I get this statement: " Hello [email] address], We have received your request to unsubscribe from privacy. However, you do not appear to be a member of privacy, so we have taken no further action."

This has happened at least twice now. I go to the support page, which it won’t let me access on my unpaid subscription account. So, I’m posting here. How can I unsubscribe from these unwanted emails?

A post was merged into an existing topic: How to unsubscribe from emails