I just had this issue yesterday and I spent way too much of my time dealing with Apple. I had to drive over a hour to get to their store only to have to make an apointment for a hour and a 1/2 later. This sucked! Then I was told it would cost $150 to fix. No thanks. I was just going to ditch the phone and start over and not with an I phone.
As I was walking out of the mall where the Apple store was I noticed a small store that had just opened that could fix it. Twenty minutes and $49 later glass was repaired. I wish I would have found this store before I wasted my day with Apple.
FYI- My phone has always been in an Otter box from day one. It dropped off my lap as I was getting out of the car and hit the ground. Not a very hard or far fall at all. I asked at both stores if there was a better case for protecting my phone. Both places told me I had the best kind of case to protect the phone. The Apple guy even questioned if I had it in the case when it broke.