The customer Used the Wrong Cleaning Product.
This problem generally occurs on sensitive stone such as marble, limestone, travertine. Using the wrong cleaning chemical can make the surface dull and create etched marks.
The customer used these two cleaner to clean shower.
This is the result:
I did the restoration with the diamonds system.
I grinded the work surface with diamond pads to remove the dull spots, etched marks and other imperfections from the surface.
I polished the working surface area with polishing powder to achieve a natural finish.
Shower looks like new: