Tile challenges

So it turns out that our awesome bargain auction tiles are slightly warped, go figure. They bulge up a little in the center. It's only barely noticeable in a few places so we decided to accept it and keep moving. However, Eric's grout selection has proved to be the next challenge. He did all of the research and decided to go with a urethane-based mortar, not the typical sand or epoxy-based types, because it doesn't fade, has more flex, can't mildew, etc. However, the installation technique is different (easier) and requires wiping any excess grout off the tiles ASAP or a haze will form that will require a lot more scrubbing after the fact. Eric explained the process to Diaz, the 2 installers and even got them instructions in Spanish, but of course they did not read them and now we're having to research methods and chemicals for haze removal. Luckily they only grouted the back bedroom and not the rest of the apartment, although this hasn't stopped him from asking for full payment (obviously, no). Tomorrow Diaz & his guys are returning to clean the hazy tiles and install the rest of the grout, hopefully with more care for the instructions this time.