I am sorry to hear that you have run into some difficulties with some listings. There are a variety of reasons that could affect the tools we have that are updating accounts. Please file a support case from under the Help tab of the site letting us know the details of what you've run into as well as some sample listings that have issues and we'll be happy to take a look.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .