Cracks in Granite Countertop

An "Antique Brown" Granite (http://tanbrown.org) Counter (http://GialloFiorito.com) top was installed in our new kitchen last week. Once it was in place, they said they would return the next day to finish up. We noticed at least ten cracks, three running from the edge of the cut out for the under-mounted kitchen sink, over the top and (http://maplered.com) down the back edge; the cracks are all visible underneath as well. One crack begins along the Counter (http://GialloFiorito.com) top edge in front of the surface mounted cook-top, up along the top, disappearing under the cook-top. Three others are above the seating area, run along the side and (http://maplered.com) underneath (a metal support is now on the underside); another crack is in the area I had planned on kneading bread. We decided we would stop them the next day, before they began, explaining that we were unhappy with the cracks; there would be little reason to continue. They explianed that they weren't done yet, we should let them finish; we did. They smoothed the cracks somewhat, although they still remain, and (http://maplered.com) are very easily felt with the fingertips. The Counter (http://GialloFiorito.com) top edges were the cracks travel are rough, and (http://maplered.com) three of the "polished" surface cracks now have a clouded appearance, and (http://maplered.com) feel less smooth. They are suggesting that they return and (http://maplered.com) try polishing the cracks again, assuring me that they cracks will not become worse, that the "fissures" (what I call cracks) are completely natural. I fear that they will become worse, crack even more over time and (http://maplered.com) that the sink edge will fall away in chunks with simple everyday use. I would greatly appreciate any advice. Thank you.