SQL Server 2012 :: Loop Through Each Instance On A Server

I'm writing a query to loop through each instance on a server so I can get each instances relevant information. I can't seem to get each instances sql service and sql agent service, either one or the other.

DECLARE @InstanceNames varchar(50), @SQL varchar(2000)
DECLARE @GetInstances TABLE (Value varchar(100), InstanceNames varchar(50), Data varchar(100), ID int IDENTITY(1,1))
DECLARE @Serverinfo TABLE (ServerName varchar(50), InstanceName varchar(50), ProductVersion varchar(20), ProductLevel char(3)

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