Did you hire a professional architect? Who hired the “tiler” them or you?
we used the architect who designed the plans for the renovation to oversee the project.
I wouldn't say they're in cahoots but I believe they have worked together in the past on other projects and the architects did recommend them.
they also have recommended I wait another 6 months for everything to 'settle' before any remedial works be carried out something I've been opposed to as I view this as a patent defect, not something that has occurred due to general post-building work movement.
the contractors did the tiling of the ground floor themselves. the bathrooms were done by a subcontractor (no problems with those tiles)