Ay no mi hjo
- with all due respect La Campagna sandwhiches aren't worth the money and half the time they put catsup on it when you tell them not too. After all, if you ask for a chicken sandwhich you don't expect to get a chicken salad one with dark meat do you? They also use the inferior Danish style cheese instead of Mozzarella and of course they charge you through the nose for an "upgrade".
To the OP: The best Italian sub sandwhich in Santiago bar none can be found off the Ave Texas in Los Jardines at a pub called Palermos. It is owned by a second or third generation Italian.
As far as tacos go, here in Santiago we say "no quiero Taco Bell, que horrible!" You best bet is to do it yourself, all the fixings you need you will find in El Nacional or El Pola. Buen provecho!