How to report Calendar invitation spam on my iPhone?

I am receiving Calendar event spam on my iPhone. The invitations don't appear in iCloud, only my iPhone and not on my MacBook Pro which is supposed to sync with my iPhone. I see three choices: Accept, Maybe, and Decline. None of these choices make any sense when I want to block or report this horrendous disgusting, rotten spam Calendar invitation. I clicked on the email address which sent the invitation but there is no means to block this address or report it as spam. Nothing. Apple needs to take seriously the spam coming into the Calendars.