We purchased a newly-renovated house with newly-laid kitchen, bathroom, and shower tiles, both floor and wall. A year after we moved in, we noticed the grout has disintegrated and the tiles were moving around. It turned out the tiles had been barely glued to the floors and walls and were mostly held together by the grout. On the upside, they came off really easily...
Ronal and his son did a great job gluing back the tiles that had become completely separated from the wall/floor and using epoxy grout in the hopes that the tiles that hadn't been properly glued but also weren't completely loose would be held together better. While I'm not sure how long this solution will hold, especially for the tiles that were not reglued from scratch, we're happy with it in the meantime and are happy we can get some more time out of these tiles without having to completely tear out our brand new kitchen and bathrooms.
The one thing to be aware of is to double check how much time is being booked for the work. I was initially told two days would be booked for the kitchen, only to later find out it was one day. Similarly, I had been told four days would be set aside for the bathrooms, only to find out that only two days had been booked. However, Ronal and Felipe worked tirelessly to get everything done in the time they were here, staying until close to 8pm one day, and managed to complete the job.