line/crack horizontally there where brick and concrete Which is it? a line, or a crack? This illustrates why a picture would be most helpful. But it doesn't sound like you're describing anything other than natural weathering away of the "dampproofing", which is virtually useless anyway.

A link is something you can click on screen to take you to a website. What you provided is only the address/URL which someone would have to copy and paste to see the site so I provided a link. Unless a brick wall is solid without a cavity for drainage it must have weeps or water will become trapped inside the wall. In a cold climate that can cause the brick to spawl and crack.

Superwhite 2014: Pull out a drawer and see if there is mesh adhered to the back of your stone. If so, I wouldn't worry about the crack, it shouldn't spread. It is natural. Those who don't like fissures should get estone or solid surface countertops. I'd grind those black blotches out with a Dremel, fill and polish them in about 15 minutes, especially if they bothered a customer so much.

If you hired a GC, it’s up to him to make it right. But, since he hired the hack, and doesnt seem to have a clue, you may want to educate yourself a lot more on how to properly waterproof and tile a wet area before you talk to him about the second tile guy he is gonna need to hire. Buy an industry bible and read it. Carry it with you prominently when you talk to the GC. https://www.tcnatile.com/products-and-services/publications/218-english-publications/188-handbook/957-2018-tcna-handbook-for-ceramic-glass-and-stone-tile-installation.html I have zero trust that a waterproofing system was installed correctly if someone does such a butcherous job on the pretty stuff that homeowners see. If they’re a visible hack where it shows, they are a worse hack where it’s hidden. Quality level of the job received has a 90% correlation with the price paid for the job. It should be a giant red flag to any homeowner when something sounds too good to be true. Especially since the information about average renovation costs is readily available. If someone is promising you a 20K job for 5K, that’s a big clue that you’re getting a 5K job. Don’t let personal greed over getting a “deal” make you start believing in the Easter Bunny. TANSTAAFL http://www.remodeling.hw.net/cost-vs-value/2018/