I think a lot of folks use the name "Corian" when they should use "solid surface." Sort of like folks saying "Xerox" when they mean "photocopier" or "Kleenex" instead of tissue.
What I would have the solid surface repair guy check is for how the solid surface is mounted to the cabinet below it. I wonder if the cabinet parts moved and placed an unnecessary strain on the solid surface, thereby causing stress cracks. A good solid surface technician will have undergone specific solid surface training and understand the proper ways to handle the product. It is a great product, but care must be taken in the design.
For those who are really interested in solid surface fabrication, try an internet search for "solid surface instructions" and look for some of the fabrication manuals put out by the solid surface manufacturers.
I have worked with solid surface for limited applications. It is easy to work with some regular woodworking tools. The shavings and dust are quite messy. What was of interest was how to mount and support the solid surface when using as a counter top. It does not work the same as a product like plastic laminate (e.g., Formica, etc.).