SQL Server 2012 Update installation fails

Windows 7 64 bit - I had SQL Server 2008 and SQL Server 2008 R2.  I uninstalled SS 2008 and tried to uninstall SS 2008 R2.  The SS2008 uninstalled fine.  The R2 said it uninstalled, but was still there.  I loaded a new version of SQL Server 2012.  Then I manually uninstalled each piece of the SS 2008 R2 except R2 Setup and one other piece because it said that 2012 used pieces of it.  Now I have a Microsoft update to SS 2012 and the update fails bc of something to do with the 2008 R2. Security Update for SQL Server 2012 RTM (KB2716442).  Installation status: Failed  Error details: Code 84B20001
I tried the Fix Windows Update, which said it worked, but the update still fails.  What should I do?  Thank you for your help.  Nancy