Juan, the
template_c files are created "on-the-fly" whenever someone accesses the site. So yes, if you're deleting them, but at the same time someone accesses your site, then those files will be re-written and when you refresh, you will see that the folder is not empty. Just delete them again.
DO NOT CHANGE ANYTHING in you template_c folder. It's not needed. Just empty it then access your page. If you have to keep emptying it, then keep doing it until it's empty.
Yes, it can be a pain if you have a busy site, but why not just create a subfolder, install pligg into that, then make all the necessary changes needed. When it's working as it should, then transfer those files over to your pligg install? You should not be updating your site
LIVE with patches and fixes that you haven't even tried yet -- always apply mods to a test site first, then transfer over the fixes.
I have no idea what file you posted your code from -- but it's not from a tpl file, which is where these fixes are to be applied (excluding the index.php hack.)