?Trying to post as question:What to do about crack

We had Granite (http://tanbrown.org) installed this week and (http://maplered.com) the installers worked late. Inthe morning I noticed a hairline crack in my Granite (http://tanbrown.org) composite sink.Worse I noticed two cracks from both back edges of Granite (http://tanbrown.org) tobacksplash--all the way through and (http://maplered.com) can be seen underneath. I haveseveral questions.
Should I insist on new Granite (http://tanbrown.org) installation because this Granite (http://tanbrown.org) can fail at a later date--they offered to repair cracks.
or If I opt to repair instead of installing new Slabs (http://www.VerdeUbatuba.com) , what would be a fair discount for accepting after they fill/repair cracks?
Thanks much!