Once they have your email you can not unsubscribe

I went to a breakfast hosted by Faith Broadcasting Network to hear Angus Buchan. They handed out contact cards, and it had an option if you do not want to be send material. I opted not to receive marketing material. However, soon I started getting e-mails from them. I now attempted to unsubscribe twice and even send them a mail to take me off their spam list. I still get their spam.