iPhone calendar Virus

Simply deleting an email account that has been hacked and shows a virus message every day in my calendar is TOTALLY unacceptable as a remedy. My calendar is just that…MY calendar and hence no one outside of my contacts and at a minimum or even those contacts should be able to mark an appointment in my calendar.

So, is there a better alternative to address this unnecessary opening other than delete the email address account OR better yet, when will a professional solution be forthcoming from Apple security?