It sounds like a pretty low end place you visited. Personally, I find this a difficult call. I do want to just have my food fixed, but at lower end places I am quite worried that this will not be the only change made to my food. At fast food type places, I just complain, get it taken care of and eat somewhere else. In a nice place, I have them recook the meal.

Having worked in that industry, I would suggest you complain. The onus is on the establishment first and foremost to feed you. In the case where they have made something you can't even eat, then they want to know.

In terms of hidden sodium, the cooking mentality is that anything that comes out of a restaurant should be seasoned. By seasoned, they mean salt and pepper. When you dine out, you will be eating high sodium foods almost without question. I'd especially avoid soups and liquid items. They require a lot of salt or else they taste too fresh.