Reddit mentions of Lustro Italiano Etch Remover

For your marble countertops, take a look at this product.

We had marble tile installed in the shower and also have marble countertops, both which were lightly damaged during the install. A harsh chemical was used on both and the marble developed light scratches and this ugly white film on it.

That polish brought everything back to brand-new. It was a TON of work, mostly because it really took some elbow grease to get the polish back and you only work in small areas at a time, but it was worth it.

Our remodel didn't take as long as yours, but it was definitely fraught with problems and by the end I just wanted the contractors gone. Sorry to hear about the problems you had. Hope you're able to get everything fixed and to your liking.

Edit: Regarding the product I recommended, it's a small tub, but a little goes a long way. I used about a tub and a half for the full shower.

You can just buff it out. $24 for a buffer at Menards

You'll need a cover for the buffer and some compound

Here's a how to a dug up. http://www.doityourself.com/stry/how-to-polish-travertine-tile

I have carrera marble in my kitchen. We just discovered a really huge etch due to a glass with vinegar sitting there all night. I did a little research and found this product really works wonders. There's a youtube video that you can watch to help you figure it out. Smaller etches come out with a few minutes of work. The larger ones may take a few applications. You have to reseal your counters afterwards as this removes all of the sealing. But you should do that yearly anyways.