Removal tool that actually removes everything

I work with a company that has an IT company that is installing their AV on our PCs. We have had Norton, but they want to change it to something else. So, we have removed Norton through add/remove programs and tried to install the new AV. The new AV still detects Norton Internet Security. We have run the Removal tool, but it still detects that there are symantec products on the PCs. We have gone through the registry and deleted everything that says Norton and Symantec and then the AV will install, but it will take a while to do every PC like that. Is there a removal tool that will actually remove Symantec AV? Can you shoot me a link or something. Thanks.